1,197 community and non-transient non-community water systems are listed for Iowa in EPA SDWIS. 153 were sampled under UCMR 5; 32 of those had at least one PFAS result at or above the reporting level, and 8 had a highest single result at or above a 2024 EPA limit (PFOA or PFOS 4 ppt, or Hazard Index 1).
Iowa map · Download: systems (CSV) · all results (CSV, gzip)
These are monitoring results collected under EPA's Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) at entry points, where treated water enters the distribution system; they are not tap-water samples. They are not compliance determinations: compliance with EPA's 2024 PFAS limits is judged on running annual averages of compliance monitoring, required from 2029, so a single UCMR 5 result at or above a limit is not a violation. “< MRL” means the compound was not quantified at EPA's minimum reporting level; it does not mean zero.
Sampled under UCMR 5 (153)
| System | PWSID | City | Population | Highest PFOA (ppt) | Highest PFOS (ppt) | Highest HI | Highest single result |
|---|---|---|---|---|---|---|---|
| Adel Municipal Water Works | IA2503003 | Adel | 6,461 | <MRL | <MRL | 0 | No PFAS detected |
| Albia Municipal Water Works | IA6803010 | Albia | 3,721 | <MRL | <MRL | 0 | Other PFAS detected |
| Algona Municipal Utilities | IA5502015 | Algona | 5,487 | <MRL | <MRL | 0 | No PFAS detected |
| Altoona Water Supply | IA7707030 | Altoona | 22,436 | <MRL | <MRL | 0 | No PFAS detected |
| Ames Water Treatment Plant | IA8503039 | Ames | 55,177 | <MRL | <MRL | 0 | No PFAS detected |
| Anamosa Municipal Water Supply | IA5307048 | Anamosa | 4,457 | <MRL | <MRL | 0 | No PFAS detected |
| Anita Municipal Utilities | IA1503053 | Anita | 972 | <MRL | <MRL | 0 | No PFAS detected |
| Ankeny, City Of | IA7709053 | Ankeny | 76,207 | <MRL | <MRL | 0 | No PFAS detected |
| Asbury Municipal Water System | IA3102001 | Asbury | 5,943 | <MRL | <MRL | 0 | No PFAS detected |
| Atlantic Municipal Utilities | IA1509074 | Atlantic | 7,252 | <MRL | <MRL | 0 | No PFAS detected |
| Bancroft Water Supply | IA5507085 | Bancroft | 711 | <MRL | <MRL | 0 | No PFAS detected |
| Belle Plaine Water Dept | IA0610099 | Belle Plaine | 2,380 | <MRL | <MRL | 0 | No PFAS detected |
| Bondurant Muni Water Supply | IA7717032 | Bondurant | 9,393 | <MRL | <MRL | 0.35 | Hazard Index below its limit |
| Boone Water Works | IA0819033 | Boone | 12,704 | <MRL | <MRL | 0 | No PFAS detected |
| Burlington Municipal Waterworks | IA2909053 | Burlington | 26,015 | <MRL | <MRL | 0.003 | Hazard Index below its limit |
| Camanche Water Supply | IA2322066 | Camanche | 4,570 | <MRL | <MRL | 0 | No PFAS detected |
| Cambridge Water Supply | IA8509069 | Cambridge | 832 | <MRL | <MRL | 0.002 | Hazard Index below its limit |
| Carlisle Water Supply | IA9113071 | Carlisle | 4,170 | <MRL | <MRL | 0.42 | Hazard Index below its limit |
| Carroll Municipal Water Supply | IA1415072 | Carroll | 10,321 | <MRL | <MRL | 0 | No PFAS detected |
| Carter Lake Water District | IA7812079 | Council Bluffs | 3,791 | <MRL | <MRL | 0 | Other PFAS detected |
| Cedar Falls Municipal Water Utilities | IA0709084 | Cedar Falls | 40,713 | <MRL | <MRL | 0 | No PFAS detected |
| Cedar Rapids Water Department | IA5715093 | Cedar Rapids | 142,364 | <MRL | <MRL | 0 | No PFAS detected |
| Centerville Municipal Waterworks | IA0407008 | Centerville | 5,344 | <MRL | <MRL | 0 | Other PFAS detected |
| Chariton Municipal Water Works | IA5903011 | Chariton | 4,381 | <MRL | <MRL | 0 | Other PFAS detected |
| Charles City Water Supply | IA3405012 | Charles City | 7,446 | <MRL | <MRL | 0 | No PFAS detected |
| Cherokee Water Supply - Plant 1 | IA1811020 | Cherokee | 5,199 | <MRL | <MRL | 0 | No PFAS detected |
| Clarinda Water Plant | IA7329029 | Clarinda | 5,305 | <MRL | <MRL | 0 | Other PFAS detected |
| Clarksville Water Supply | IA1228038 | Marshalltown | 1,254 | <MRL | <MRL | 0 | No PFAS detected |
| Clear Lake Water Department | IA1716076 | Clear Lake | 7,687 | <MRL | <MRL | 0 | No PFAS detected |
| Clermont Water Supply | IA3317047 | Clermont | 586 | <MRL | <MRL | 0 | No PFAS detected |
| Clive Water Department | IA7720051 | Clive | 20,277 | <MRL | <MRL | 0 | No PFAS detected |
| Coralville Muni Water System | IA5208071 | Coralville | 22,318 | <MRL | <MRL | 0 | No PFAS detected |
| Council Bluffs Water Works | IA7820080 | Council Bluffs | 64,447 | <MRL | <MRL | 0 | No PFAS detected |
| Cresco Waterworks | IA4515087 | Cresco | 3,913 | <MRL | <MRL | 0 | No PFAS detected |
| Creston Water Supply | IA8816089 | Creston | 7,536 | <MRL | <MRL | 0 | Other PFAS detected |
| De Witt Water Supply | IA2330036 | Dewitt | 5,514 | <MRL | <MRL | 0 | No PFAS detected |
| Decorah Water Department | IA9630012 | Decorah | 7,615 | <MRL | <MRL | 0.004 | Hazard Index below its limit |
| Denison Water Supply | IA2424027 | Denison | 9,381 | <MRL | <MRL | 0 | No PFAS detected |
| Des Moines Water Works | IA7727031 | Des Moines | 246,055 | <MRL | <MRL | 0 | No PFAS detected |
| Dubuque Water Works | IA3126052 | Dubuque | 59,667 | 5.1 | <MRL | 0 | PFOA 1–3 × its limit |
| Dyersville Municipal Water Co | IA3130091 | Dyersville | 4,477 | <MRL | <MRL | 0 | No PFAS detected |
| Eagle Grove Water Supply | IA9926096 | Eagle Grove | 3,601 | <MRL | <MRL | 0 | No PFAS detected |
| Eldridge Water Supply | IA8230008 | Eldridge | 6,726 | <MRL | <MRL | 0 | No PFAS detected |
| Emmetsburg Municipal Water Department | IA7428021 | Emmetsburg | 3,733 | <MRL | <MRL | 0 | No PFAS detected |
| Estherville Water Treatment Plant | IA3218024 | Estherville | 5,974 | <MRL | <MRL | 0 | No PFAS detected |
| Evansdale Water Works | IA0723027 | Evansdale | 4,561 | <MRL | <MRL | 0 | No PFAS detected |
| Fairfield Water Supply | IA5131033 | Fairfield | 9,821 | <MRL | <MRL | 0 | No PFAS detected |
| Forest City Water Supply | IA9525047 | Forest City | 4,285 | <MRL | <MRL | 0 | No PFAS detected |
| Fort Dodge Water Supply | IA9433050 | Fort Dodge | 25,874 | <MRL | <MRL | 0 | No PFAS detected |
| Ft Madison Muni Water Works | IA5625062 | Fort Madison | 11,087 | <MRL | <MRL | 0 | No PFAS detected |
| Garden Grove Water Supply | IA2725073 | Allerton | 184 | <MRL | <MRL | 0 | Other PFAS detected |
| Glenwood Municipal Utilities | IA6525090 | Glenwood | 5,449 | <MRL | <MRL | 0 | No PFAS detected |
| Grimes Water Supply | IA7736011 | Grimes | 17,997 | <MRL | <MRL | 0 | No PFAS detected |
| Grinnell Water Department | IA7930008 | Grinnell | 9,564 | <MRL | <MRL | 0 | No PFAS detected |
| Hampton Muni Water Works | IA3544024 | Hampton | 4,337 | <MRL | <MRL | 0 | No PFAS detected |
| Harlan Municipal Utilities | IA8335029 | Harlan | 5,067 | <MRL | <MRL | 0 | No PFAS detected |
| Hiawatha Water Dept | IA5735045 | Hiawatha | 7,183 | <MRL | <MRL | 0.37 | Hazard Index below its limit |
| Humboldt Municipal Water Dept | IA4641064 | Humboldt | 4,792 | <MRL | <MRL | 0 | No PFAS detected |
| Huxley Waterworks Dept | IA8538066 | Huxley | 4,244 | <MRL | <MRL | 0 | No PFAS detected |
| Ia Regional Utilities Assoc (Waverly) | IA0990701 | Newton | 37,820 | <MRL | <MRL | 0 | No PFAS detected |
| Independence Water Dept | IA1037070 | Independence | 6,064 | <MRL | <MRL | 0 | No PFAS detected |
| Indianola Water Supply | IA9133075 | Indianola | 15,833 | <MRL | <MRL | 0 | No PFAS detected |
| Iowa City Mhp Llc | IA5200601 | Oxford | 280 | <MRL | <MRL | 0 | No PFAS detected |
| Iowa City Water Department | IA5225079 | Iowa City | 68,753 | <MRL | <MRL | 0 | No PFAS detected |
| Iowa Falls Water Department | IA4260097 | Iowa Falls | 5,146 | <MRL | <MRL | 0 | No PFAS detected |
| Iowa Lakes Regional Water | IA2100701 | Spencer | 6,755 | <MRL | <MRL | 0 | No PFAS detected |
| Iowa Lakes Regional Water - Osgood | IA3060001 | Spencer | 9,021 | <MRL | <MRL | 0 | Other PFAS detected |
| Iowa Premium Llc | IA8670101 | Tama | 841 | <MRL | <MRL | 0 | No PFAS detected |
| Iowa-American Wtr Co-Clinton District | IA2326048 | Clinton | 24,769 | <MRL | <MRL | 0.006 | Hazard Index below its limit |
| Iowa-American Wtr Co-Davenport | IA8222001 | Davenport | 147,720 | 4.1 | <MRL | 0 | PFOA 1–3 × its limit |
| Isu | IA8503528 | Ames | 42,000 | <MRL | <MRL | 0 | No PFAS detected |
| Jefferson Water Department | IA3742004 | Jefferson | 4,182 | <MRL | <MRL | 0 | No PFAS detected |
| Johnston Municipal Water Supply | IA7740011 | Johnston | 24,897 | <MRL | <MRL | 0 | No PFAS detected |
| Keokuk Municipal Water Works | IA5640019 | Keokuk | 9,900 | <MRL | <MRL | 0.003 | Hazard Index below its limit |
| Knoxville Water Works | IA6342036 | Knoxville | 8,400 | <MRL | <MRL | 0 | No PFAS detected |
| Lemars Water Department | IA7540174 | Lemars | 10,606 | <MRL | <MRL | 0 | No PFAS detected |
| Lyon-Sioux Rws-Big Sioux | IA6000755 | Rock Rapids | 1,530 | <MRL | <MRL | 0 | No PFAS detected |
| Mahaska Rural Water System, Inc. | IA6273901 | Oskaloosa | 11,325 | <MRL | <MRL | 0 | No PFAS detected |
| Manchester Water Supply | IA2839021 | Manchester | 5,077 | <MRL | <MRL | 0 | No PFAS detected |
| Maquoketa Municipal Water | IA4950029 | Maquoketa | 6,128 | <MRL | <MRL | 0 | No PFAS detected |
| Marion Co. Rural Water District | IA6342711 | Knoxville | 5,687 | <MRL | <MRL | 0 | No PFAS detected |
| Marion Municipal Water Dept | IA5751035 | Marion | 41,623 | <MRL | <MRL | 0 | No PFAS detected |
| Marshalltown Water Works | IA6469042 | Marshalltown | 27,680 | <MRL | <MRL | 0 | No PFAS detected |
| Mason City Water Department | IA1750048 | Mason City | 27,338 | <MRL | <MRL | 0 | No PFAS detected |
| Melcher-Dallas Water Supply | IA6300099 | Melcher Dallas | 1,213 | <MRL | <MRL | 0 | No PFAS detected |
| Monticello Water Supply | IA5343098 | Monticello | 4,040 | <MRL | <MRL | 0 | No PFAS detected |
| Mount Pleasant Municipal Utilities | IA4453016 | Mount Pleasant | 9,274 | <MRL | <MRL | 0 | No PFAS detected |
| Mount Vernon Water Supply | IA5758021 | Mount Vernon | 4,527 | <MRL | <MRL | 0 | No PFAS detected |
| Muscatine Power & Water | IA7048001 | Muscatine | 25,516 | 7.2 | 4.5 | 0.003 | PFOA 1–3 × its limit |
| Nevada Water Supply | IA8562044 | Nevada | 6,925 | <MRL | <MRL | 0 | No PFAS detected |
| New Hampton Water Supply | IA1970051 | New Hampton | 3,494 | <MRL | <MRL | 0 | No PFAS detected |
| Newton Water Supply | IA5059064 | Newton | 16,518 | <MRL | <MRL | 0 | No PFAS detected |
| North Liberty Water Supply | IA5252072 | North Liberty | 23,276 | <MRL | <MRL | 0 | No PFAS detected |
| Norwalk Water Supply | IA9164078 | Norwalk | 14,334 | <MRL | <MRL | 0 | No PFAS detected |
| Oelwein Municipal Water Works | IA3353088 | Oelwein | 5,920 | <MRL | <MRL | 0 | No PFAS detected |
| Okoboji Water Supply | IA3060091 | Okoboji | 776 | <MRL | <MRL | 0 | Other PFAS detected |
| Onawa Municipal Water Plant | IA6739095 | Onawa | 2,906 | <MRL | <MRL | 0 | No PFAS detected |
| Orange City Municipal Water Department | IA8474097 | Orange City | 6,267 | <MRL | <MRL | 0 | No PFAS detected |
| Osage Municipal Water Supply | IA6663001 | Osage | 3,637 | <MRL | 4.2 | 0.43 | PFOS 1–3 × its limit |
| Osceola Rural Water System-North | IA7227701 | May City | 7,002 | <MRL | <MRL | 0 | No PFAS detected |
| Osceola Water Works | IA2038038 | Osceola | 5,503 | <MRL | <MRL | 0 | Other PFAS detected |
| Oskaloosa Municipal Water Dept | IA6273005 | Oskaloosa | 12,808 | <MRL | <MRL | 0 | No PFAS detected |
| Ottumwa Water Works | IA9083012 | Ottumwa | 25,529 | <MRL | <MRL | 0 | No PFAS detected |
| Pella Water Works Department | IA6368033 | Pella | 11,052 | <MRL | <MRL | 0 | No PFAS detected |
| Perry Municipal Water Works | IA2561036 | Perry | 7,836 | <MRL | <MRL | 0 | No PFAS detected |
| Polk City Water Supply | IA7770050 | Polk City | 6,533 | <MRL | <MRL | 0 | No PFAS detected |
| Portsmouth Water Supply | IA8365052 | Panama | 189 | <MRL | <MRL | 0 | No PFAS detected |
| Poweshiek Water Association | IA8670701 | Tama | 13,920 | <MRL | <MRL | 0 | No PFAS detected |
| Rathbun Reg Water Assn (Ft Madison) | IA0400901 | Centerville | 11,840 | <MRL | <MRL | 0 | Other PFAS detected |
| Rathbun Reg Wtr Assn (Burlington) | IA0400902 | Centerville | 8,375 | <MRL | <MRL | 0 | Other PFAS detected |
| Rathbun Regional Water Assn (Rathbun) | IA0400900 | Centerville | 33,000 | <MRL | <MRL | 0 | No PFAS detected |
| Red Oak Water Supply | IA6950075 | Red Oak | 5,596 | <MRL | <MRL | 0 | No PFAS detected |
| Regional Water | IA8300184 | Avoca | 4,132 | <MRL | <MRL | 0 | No PFAS detected |
| Riverview Subdivision | IA7038301 | Muscatine | 37 | <MRL | <MRL | 0 | No PFAS detected |
| Rock Valley Water Supply | IA8482096 | Rock Valley | 4,059 | <MRL | <MRL | 0 | No PFAS detected |
| Rural Water System #1 | IA8400722 | Hospers | 3,428 | <MRL | <MRL | 0 | No PFAS detected |
| Sac & Fox (Meskwaki) In Iowa | 070000003 | Tama | 4,765 | <MRL | <MRL | 0 | No PFAS detected |
| Sergeant Bluff Water Supply | IA9774033 | Sergeant Bluff | 5,015 | <MRL | <MRL | 0 | No PFAS detected |
| Sheldon Water Department | IA7170040 | Sheldon | 5,512 | <MRL | <MRL | 0 | No PFAS detected |
| Shenandoah Water Dept | IA7383045 | Shenandoah | 4,933 | <MRL | <MRL | 0 | No PFAS detected |
| Sioux Center Municipal Water Department | IA8486053 | Sioux Center | 8,231 | <MRL | <MRL | 0 | No PFAS detected |
| Sioux City Water Supply | IA9778054 | Sioux City | 85,791 | 6 | 4.3 | 3.51 | Hazard Index ≥ 3 × its limit |
| Sirwa #2 (Creston) | IA8080701 | Creston | 20,793 | <MRL | <MRL | 0 | No PFAS detected |
| Sirwa #3 (Osceola) | IA2038701 | Creston | 4,080 | <MRL | <MRL | 0 | Other PFAS detected |
| Southeast Polk Rwd | IA7774701 | Des Moines | 7,565 | <MRL | <MRL | 0 | No PFAS detected |
| Southern Sioux County Rural Water | IA8400733 | Ireton | 5,420 | <MRL | <MRL | 0 | No PFAS detected |
| Spencer Municipal Water Utility | IA2171071 | Spencer | 11,325 | <MRL | <MRL | 0 | No PFAS detected |
| Spirit Lake Waterworks | IA3070078 | Spirit Lake | 6,167 | <MRL | <MRL | 0 | Other PFAS detected |
| Storm Lake Water Treatment Plant | IA1178097 | Storm Lake | 11,431 | <MRL | <MRL | 0 | No PFAS detected |
| Story City Water Dept | IA8584000 | Story City | 3,357 | <MRL | <MRL | 0 | No PFAS detected |
| University Water System | IA5225101 | Iowa City | 47,136 | <MRL | <MRL | 0 | No PFAS detected |
| Urban Bluffs - North | IA7820701 | Avoca | 1,558 | <MRL | <MRL | 0.002 | Hazard Index below its limit |
| Urbandale Water Utility | IA7780042 | Urbandale | 45,605 | <MRL | <MRL | 0 | No PFAS detected |
| Vinton Municipal Water Dept | IA0688053 | Vinton | 4,938 | <MRL | <MRL | 0 | No PFAS detected |
| Wapello Rural Water Assoc. | IA9000742 | Ottumwa | 17,263 | <MRL | <MRL | 0 | Other PFAS detected |
| Warren Water District | IA9133701 | Indianola | 20,095 | <MRL | <MRL | 0 | No PFAS detected |
| Washington Water Department | IA9271068 | Washington | 7,362 | <MRL | <MRL | 0 | No PFAS detected |
| Waterloo Water Works | IA0790074 | Waterloo | 69,504 | <MRL | <MRL | 1.302 | Hazard Index 1–3 × its limit |
| Waukee Water Supply | IA2573080 | Waukee | 31,823 | <MRL | <MRL | 0 | No PFAS detected |
| Waukon Water Department | IA0398082 | Waukon | 3,827 | <MRL | <MRL | 0 | No PFAS detected |
| Waverly Water Department | IA0990085 | Waverly | 10,394 | 7.2 | <MRL | 1.5 | PFOA 1–3 × its limit |
| Webster City Water Supply | IA4063094 | Webster City | 7,825 | <MRL | <MRL | 0 | No PFAS detected |
| West Burlington Muni. Water Supply | IA2985002 | West Burlington | 3,555 | 5.3 | <MRL | 0.002 | PFOA 1–3 × its limit |
| West Central Rwa - Nish System | IA1400902 | Manning | 3,573 | <MRL | <MRL | 0 | No PFAS detected |
| West Central Rwa-Boyer System | IA1400903 | Manning | 1,715 | <MRL | <MRL | 0 | No PFAS detected |
| West Des Moines Water Works | IA7785007 | West Des Moines | 73,959 | <MRL | <MRL | 0 | No PFAS detected |
| West Liberty Water Utility | IA7073010 | West Liberty | 3,938 | <MRL | <MRL | 0 | No PFAS detected |
| Winterset Municipal Waterworks | IA6171029 | Winterset | 5,428 | <MRL | <MRL | 0 | No PFAS detected |
| Worth Co Interchange 214 Water Supply | IA9855202 | Manly | 3,850 | <MRL | <MRL | 0 | No PFAS detected |
| Xenia Rwd (Boone) | IA0844006 | Bouton | 4,975 | <MRL | <MRL | 0 | No PFAS detected |
| Xenia Rwd (Des Moines) | IA2573701 | Bouton | 12,860 | <MRL | <MRL | 0 | No PFAS detected |
| Xenia Rwd (North) | IA9425701 | Bouton | 6,122 | <MRL | <MRL | 0 | No PFAS detected |
| Xenia Rwd (Woodward) | IA2576705 | Bouton | 3,465 | <MRL | <MRL | 0 | No PFAS detected |
Not tested under UCMR 5 (1,044)
UCMR 5 required monitoring by systems serving 3,300 or more people and by a representative sample of smaller systems. The systems below have no UCMR 5 results in EPA's data. Not tested is not the same as not detected: the absence of results says nothing about PFAS in their water.
| System | PWSID | Type | City | Population | Counties |
|---|---|---|---|---|---|
| 200 East 90Th St, Llc | IA8222174 | NTNCWS | Long Grove | 425 | Scott County |
| Absolute Energy Llc | IA6649801 | NTNCWS | St Ansgar | 70 | Mitchell County |
| Ace Mobile Home Park | IA3100629 | CWS | Dubuque | 32 | Dubuque County |
| Ackley Municipal Water Works | IA4201001 | CWS | Marshalltown | 1,599 | Hardin County |
| Adair Municipal Water Supply | IA0105002 | CWS | Adair | 809 | Adair County |
| Ag Processing - Refinery | IA9774003 | NTNCWS | Sergeant Bluff | 50 | Woodbury County |
| Ag Processing - Soy Plant | IA9774002 | NTNCWS | Sergeant Bluff | 110 | Woodbury County |
| Ag Processing Inc - Algona | IA5502101 | NTNCWS | Algona | 49 | Kossuth County |
| Agency Water Works | IA9003006 | CWS | Agency | 620 | Wapello County |
| Agri Star Meat And Poultry Llc | IA0375180 | NTNCWS | Ossian | 550 | Allamakee County |
| Ainsworth Water Works | IA9203007 | CWS | Ainsworth | 511 | Washington County |
| Akron, City Of | IA7509008 | CWS | Akron | 1,558 | Plymouth County |
| Albert City Muni Water Supply | IA1103009 | CWS | Albert City | 677 | Buena Vista County |
| Albion Water Department | IA6403011 | CWS | Albion | 448 | Marshall County |
| Alburnett Water Supply | IA5704012 | CWS | Alburnett | 675 | Linn County |
| Alden Water Supply | IA4213013 | CWS | Alden | 764 | Hardin County |
| Alexander Water Dept | IA3503014 | CWS | Manly | 164 | Franklin County |
| Allerton Water Works | IA9303024 | CWS | Allerton | 430 | Wayne County |
| Allison Water Supply | IA1203026 | CWS | Allison | 966 | Butler County |
| Alpine Park | IA3126605 | CWS | Epworth | 932 | Dubuque County |
| Alta Municipal Water Plant | IA1108025 | CWS | Alta | 2,087 | Buena Vista County |
| Alta Vista Water Department | IA1903027 | CWS | Alta Vista | 227 | Chickasaw County |
| Alton Municipal Water Department | IA8403029 | CWS | Alton | 1,248 | Sioux County |
| Alvord Municipal Water Supply | IA6003032 | CWS | Alvord | 206 | Lyon County |
| Amana Society Water System North | IA4848001 | CWS | Amana | 1,248 | Iowa County |
| Anamosa State Penitentiary | IA5300947 | CWS | Anamosa | 1,230 | Jones County |
| Andover Water Supply | IA2307001 | CWS | Miles | 109 | Clinton County |
| Andrew Water Supply | IA4903050 | CWS | Marshalltown | 380 | Jackson County |
| Anthon Municipal Water System | IA9704060 | CWS | Anthon | 545 | Woodbury County |
| Aplington Water Supply | IA1207061 | CWS | Aplington | 1,126 | Butler County |
| Arcadia Water Supply | IA1403062 | CWS | Arcadia | 525 | Carroll County |
| Arlington Water Supply | IA3307065 | CWS | Arlington | 419 | Fayette County |
| Armstrong Water Supply | IA3203066 | CWS | Armstrong | 918 | Emmet County |
| Arnolds Park Water Department | IA3003067 | CWS | Arnolds Park | 1,113 | Dickinson County |
| Arthur Municipal Water Supply | IA4703068 | CWS | Newell | 222 | Ida County |
| Ashton Municipal Water Department | IA7209069 | CWS | Ashton | 456 | Osceola County |
| Atalissa Municipal Water Supply | IA7009071 | CWS | Tipton | 296 | Muscatine County |
| Atkins Municipal Water Works | IA0603072 | CWS | Atkins | 2,056 | Benton County |
| Atlantic Head Start | IA1509501 | NTNCWS | Atlantic | 25 | Cass County |
| Auburn Water Supply | IA8104076 | CWS | Auburn | 265 | Sac County |
| Audubon Water Supply | IA0505077 | CWS | Audubon | 2,053 | Audubon County |
| Aurelia Water Supply | IA1803079 | CWS | Aurelia | 968 | Cherokee County |
| Autumn Ridge Estates Mhp | IA7709601 | CWS | Grinnell | 1,032 | Polk County |
| Avoca Water Works | IA7803080 | CWS | Avoca | 1,697 | Pottawattamie County |
| Bacon Addition | IA5343301 | CWS | Monticello | 81 | Jones County |
| Badger Water Supply | IA9405082 | CWS | Badger | 561 | Webster County |
| Baldwin Water Supply | IA4907084 | CWS | Wyoming | 99 | Jackson County |
| Barnes City Water Supply | IA7905088 | CWS | Deep River | 156 | Mahaska County, Poweshiek County |
| Barnum Water Supply | IA9408087 | CWS | Fort Dodge | 175 | Webster County |
| Batavia Water Works | IA5107089 | CWS | Batavia | 430 | Jefferson County |
| Battle Creek Water Supply | IA4709090 | CWS | Battle Creek | 700 | Ida County |
| Baxter Water Supply | IA5003091 | CWS | Baxter | 1,002 | Jasper County |
| Bayard Water Supply | IA3907092 | CWS | Adair | 405 | Guthrie County |
| Beaman Water Supply | IA3803094 | CWS | Beaman | 161 | Grundy County |
| Becker Drive Road & Well, Llc | IA9433312 | CWS | Humboldt | 50 | Webster County |
| Bedford Water Works | IA8709096 | CWS | Bedford | 1,533 | Taylor County |
| Beeds Lake Home Owners Association | IA3500933 | CWS | Hampton | 75 | Franklin County |
| Bellevue Municipal Utilities | IA4910000 | CWS | Bellevue | 2,363 | Jackson County |
| Belmond Water Supply | IA9905003 | CWS | Belmond | 2,463 | Wright County |
| Benefit Water District #2 | IA0819305 | CWS | Ames | 100 | Boone County |
| Bennett Waterworks | IA1603005 | CWS | Lowden | 347 | Cedar County |
| Berea Heights Inc | IA9778301 | CWS | Sioux City | 33 | Woodbury County |
| Bernard Water System | IA3113001 | CWS | Bernard | 114 | Dubuque County |
| Bertram Water Supply | IA5710001 | CWS | Van Horne | 75 | Linn County |
| Beyonder Getaway At Sleepy Hollow | IA5260601 | CWS | Oxford | 70 | Johnson County, Keokuk County |
| Big Creek Bluffs | IA5784309 | CWS | Cedar Rapids | 80 | Linn County |
| Big River United Energy Llc | IA3130802 | NTNCWS | Dyersville | 50 | Delaware County |
| Birmingham Water Supply | IA8909011 | CWS | Birmingham | 367 | Van Buren County |
| Blackbird Bend Casino | 070000017 | NTNCWS | Onawa | 546 | |
| Blairs Ferry Manor | IA5784316 | CWS | Urbana | 65 | Linn County |
| Blairsburg Water Supply | IA4003012 | CWS | Ellsworth | 177 | Hamilton County |
| Blairstown Water Supply | IA0607013 | CWS | Blairstown | 738 | Benton County |
| Blakesburg Municipal Water Works | IA9027014 | CWS | Blakesburg | 305 | Wapello County |
| Blencoe Municipal Waterworks | IA6709017 | CWS | Blencoe | 224 | Monona County |
| Bloomfield Muni Water Dept | IA2613019 | CWS | Bloomfield | 2,792 | Davis County |
| Bode Municipal Water Supply | IA4609028 | CWS | Livermore | 304 | Humboldt County |
| Bonaparte Water Supply | IA8914031 | CWS | Washinginton | 390 | Van Buren County |
| Boyden Municipal Water Supply | IA8409037 | CWS | Boyden | 709 | Sioux County |
| Braddyville Water Works | IA7324038 | CWS | Braddyville | 147 | Page County |
| Brandon Water Supply | IA1011001 | CWS | Brandon | 341 | Buchanan County |
| Brayton Water System | IA0510040 | CWS | Brayton | 143 | Audubon County |
| Breda Water Supply | IA1409041 | CWS | Breda | 502 | Carroll County |
| Breezy Pointe Subdivision | IA2258603 | CWS | Waukon | 130 | Clayton County |
| Brighton Municipal Water Supply | IA9209043 | CWS | Brighton | 600 | Washington County |
| Bristow Muni Water Supply | IA1222044 | CWS | Bristow | 145 | Butler County |
| Britt Water Works | IA4103045 | CWS | Britt | 2,064 | Hancock County |
| Brittany Estates Homeowners Association | IA5715301 | CWS | Cedar Rapids | 72 | Linn County |
| Bronson Water Supply | IA9709046 | CWS | Bronson | 294 | Woodbury County |
| Brookhill Estates | IA2330301 | CWS | Leclaire | 41 | Clinton County |
| Brooklyn Water Department | IA7909047 | CWS | Brooklyn | 1,505 | Poweshiek County |
| Brunsville Municipal Water Supply | IA7514049 | CWS | Storm Lake | 129 | Plymouth County |
| Buffalo Center Muni Water Dept | IA9506052 | CWS | Whittemore | 857 | Winnebago County |
| Buffalo Water Supply | IA8218050 | CWS | Buffalo | 1,176 | Scott County |
| Burds Green Acres Subdivision | IA3170302 | CWS | Peosta | 312 | Dubuque County |
| Burt Water Supply | IA5510060 | CWS | Burt | 418 | Kossuth County |
| Bussey Water Supply | IA6309061 | CWS | Oskaloosa | 427 | Marion County |
| Calamus Water Supply | IA2320062 | CWS | Calamus | 356 | Clinton County |
| Callender Water Supply | IA9417063 | CWS | Fort Dodge | 371 | Webster County |
| Calmar Water Supply | IA9615064 | CWS | Calmar | 1,125 | Winneshiek County |
| Calumet Water Supply | IA7109065 | CWS | Calument | 146 | O'Brien County |
| Camp Dodge Water Supply | IA7700901 | CWS | Johnston | 1,169 | Polk County |
| Camp Granada | IA3100605 | NTNCWS | Dubuque | 76 | Dubuque County |
| Cantril Water Supply | IA8920001 | CWS | Cantril | 224 | Van Buren County |
| Cardinal Valley Estates 3Rd Addition | IA2330303 | CWS | De Witt | 25 | Clinton County |
| Cargill Salt | IA8218101 | NTNCWS | Buffalo | 59 | Scott County |
| Carlton Mobile Home Court | IA5700601 | CWS | Springville | 85 | Linn County |
| Carriage Meadows Homeowners Association | IA8209309 | CWS | Bettendorf | 80 | Scott County |
| Carriage Place Estates Hoa | IA8209307 | CWS | Davenport | 125 | Scott County |
| Carson Water Supply | IA7809078 | CWS | Carson | 766 | Pottawattamie County |
| Cascade Municipal Water Supply | IA3118080 | CWS | Cascade | 2,386 | Dubuque County, Jones County |
| Casey Water Supply | IA3914081 | CWS | Casey | 387 | Adair County, Guthrie County |
| Castalia Water Works | IA9620082 | CWS | Ossian | 145 | Winneshiek County |
| Castana Municipal Water Supply | IA6715083 | CWS | Castana | 103 | Monona County |
| Cedar Falls Mobile Home Village | IA0709600 | CWS | Waverly | 388 | Black Hawk County |
| Cedar Terrace Mhc | IA5700600 | CWS | Newton | 600 | Linn County |
| Center Junction (Eiruss) | IA5315005 | CWS | Wyoming | 100 | Jones County |
| Center Point Water Supply | IA5718006 | CWS | Center Point | 2,579 | Linn County |
| Central City Water Supply | IA5720010 | CWS | Central City | 1,264 | Linn County |
| Central Iowa Power Cooperative | IA5715103 | NTNCWS | Dewitt | 56 | Linn County |
| Central Water System | IA3000099 | CWS | Okoboji | 25 | Dickinson County |
| Central Water Works | IA9400801 | CWS | Fort Dodge | 27 | Webster County |
| Chain Ridge Subdivision | IA5282307 | CWS | Solon | 25 | Johnson County |
| Charlotte Water Works | IA2324016 | CWS | Maquoketa | 401 | Clinton County |
| Charter Oak Water Supply | IA2417018 | CWS | Charter Oak | 522 | Crawford County |
| Chase Mobile Home Park | IA4260602 | CWS | Iowa Falls | 85 | Hardin County |
| Chelsea Water Supply | IA8609019 | CWS | Chelsea | 229 | Tama County |
| Cherokee Rws - Cherokee Subsystem | IA1811001 | CWS | Cherokee | 3,315 | Cherokee County |
| Cherokee Rws- Mill Creek Subsystem | IA1800900 | CWS | Cherokee | 1,451 | Cherokee County |
| Cherry Hills Subdivision | IA5225305 | CWS | Iowa City | 59 | Johnson County |
| Chester Water Supply | IA4509024 | CWS | Riceville | 139 | Howard County |
| Chestnut Ridge | IA5784312 | CWS | Cedar Rapids | 33 | Linn County |
| Churdan Water Supply | IA3709001 | CWS | Churdan | 375 | Greene County |
| Cincinnati Municipal Water Co | IA0410026 | CWS | Cincinnati | 290 | Appanoose County |
| City Of Kalona - Southtown | IA9233460 | CWS | Kalona | 60 | Washington County |
| Ciww ( Polk City) | IA7770052 | CWS | Polk City | 25 | Polk County |
| Ciww (Dmww) | IA7727033 | CWS | Des Moines | 25 | Polk County |
| Ciww (Grimes) | IA7736015 | CWS | Grimes | 25 | Polk County |
| Ciww (Wdmww) | IA7785009 | CWS | West Des Moines | 25 | Polk County |
| Clare Water Department | IA9420027 | CWS | Ft Dodge | 136 | Webster County |
| Clarence Water Supply | IA1630028 | CWS | Mechanicsville | 1,039 | Cedar County |
| Clarinda Treatment Complex | IA7329501 | CWS | Clarinda | 1,439 | Page County |
| Clarion Water Supply | IA9909031 | CWS | Clarion | 2,810 | Wright County |
| Clayton Water Supply | IA2203039 | CWS | Clayton | 45 | Clayton County |
| Clear Creek Mhp | IA5288601 | CWS | Oxford | 173 | Johnson County |
| Cleghorn Water Supply | IA1817045 | CWS | Storm Lake | 247 | Cherokee County |
| Clemons Water Supply | IA6415046 | CWS | Clemons | 140 | Marshall County |
| Clover Ridge Subdivision | IA0690301 | CWS | Muscatine | 413 | Benton County |
| Clutier Water Supply | IA8616052 | CWS | Clutier | 213 | Tama County |
| Coach Road Well Association | IA1600301 | CWS | Lisbon | 60 | Cedar County |
| Coal Valley Water District | IA0819303 | CWS | Ogden | 240 | Boone County |
| Cody Elementary School | IA8271565 | NTNCWS | Leclaire | 400 | Scott County |
| Coggon Water Department | IA5722053 | CWS | Coggon | 701 | Linn County |
| Coin Water Supply | IA7335054 | CWS | Shenandoah | 176 | Page County |
| Colesburg Water Supply | IA2809055 | CWS | Colesburg | 386 | Delaware County |
| Colfax Water Supply | IA5009056 | CWS | Colfax | 2,305 | Jasper County |
| College Springs Water Supply | IA7341059 | CWS | Clarinda | 170 | Page County |
| Collins Water Supply | IA8515060 | CWS | Collins | 505 | Story County |
| Colo Water Supply | IA8520061 | CWS | Colo | 853 | Story County |
| Colonial Terrace Mhp Llc | IA6342601 | CWS | Knoxville | 250 | Marion County |
| Columbus City Public Water Supply | IA5809063 | CWS | Olds | 392 | Louisa County |
| Columbus Junction Water Supply | IA5815064 | CWS | Columbus Junction | 1,830 | Louisa County |
| Colwell, City Of | IA3409066 | CWS | Alta Vista | 55 | Floyd County |
| Conagra Foods Packaged Foods Llc | IA5625141 | NTNCWS | Fort Madison | 540 | Lee County |
| Conrad Water Supply | IA3809067 | CWS | Conrad | 1,098 | Grundy County |
| Coon Rapids Municipal Utilities | IA1427070 | CWS | Coon Rapids | 1,242 | Carroll County |
| Coralville Lake Manor | IA5200825 | CWS | Oxford | 170 | Johnson County |
| Coralville Lake Terrace | IA5200817 | CWS | Tipton | 340 | Johnson County |
| Corning Muni Water Department | IA0220075 | CWS | Corning | 1,735 | Adams County |
| Corporation Of New Melleray | IA3100899 | NTNCWS | Peosta | 89 | Dubuque County |
| Correctionville Water Supply | IA9721076 | CWS | Correctionville | 766 | Woodbury County |
| Corridor Ridge Subdivision | IA5280303 | CWS | Muscatine | 108 | Johnson County |
| Corwith Water Supply | IA4109077 | CWS | Corwith | 266 | Hancock County |
| Corydon Water Supply | IA9334078 | CWS | Corydon | 1,610 | Wayne County |
| Cottage Reserve Corporation | IA5200801 | CWS | Solon | 198 | Johnson County |
| Coulter Water Supply | IA3525079 | CWS | Coulter | 219 | Franklin County |
| Country Estates Mhp | IA8200601 | CWS | Davenport | 100 | Scott County |
| Country Estates Mobile Home Park | IA6500600 | CWS | Glenwood | 35 | Mills County, Pottawattamie County |
| Country Hills Water Corp | IA3122301 | CWS | Peosta | 38 | Dubuque County |
| Country Manor Estates | IA5784307 | CWS | Cedar Rapids | 228 | Linn County |
| Country View Subdivision Hoa | IA9233899 | CWS | Kalona | 55 | Johnson County |
| Craig Water Works | IA7521084 | CWS | Craig | 79 | Plymouth County |
| Crawfordsville Water Supply | IA9214085 | CWS | Washington | 277 | Washington County |
| Crescent Water Supply | IA7822086 | CWS | Marshalltown | 778 | Pottawattamie County |
| Crestwood Acres | IA5784314 | CWS | Cedar Rapids | 50 | Linn County |
| Crystal Lake Water Supply | IA4115092 | CWS | Thompson | 255 | Hancock County |
| Cumberland Ridge First Addition | IA5252301 | CWS | North Liberty | 55 | Johnson County |
| Cumberland Water Supply | IA1516093 | CWS | Cumberland | 266 | Cass County |
| Cushing Water Supply | IA9725094 | CWS | Storm Lake | 230 | Woodbury County |
| Dakota City Water Supply | IA4622095 | CWS | Dakota City | 769 | Humboldt County |
| Dallas Center Water Supply | IA2520098 | CWS | Dallas Center | 1,901 | Dallas County |
| Danbury Water Supply | IA9729099 | CWS | Danbury | 320 | Woodbury County |
| Dans Overhead Doors | IA5252203 | NTNCWS | Tipton | 110 | Johnson County |
| Danville Water Supply | IA2915000 | CWS | Muscatine | 923 | Des Moines County |
| Dawson Water Works | IA2525010 | CWS | Dawson | 116 | Dallas County |
| Daybreak Foods Eagle Grove Complex | IA9926801 | NTNCWS | Gilmore City | 210 | Wright County |
| Daybreak Foods Inc | IA7445101 | NTNCWS | Graettinger | 65 | Palo Alto County |
| Daybreak Foods Vincent Complex | IA9926802 | NTNCWS | Gilmore City | 60 | Wright County |
| Dayton Municipal Water Supply | IA9425011 | CWS | Fort Dodge | 772 | Webster County |
| De Soto Water Supply | IA2529035 | CWS | Adel | 960 | Dallas County |
| Dedham Water Supply | IA1433016 | CWS | Dedham | 221 | Carroll County |
| Deep River Water Supply | IA7915017 | CWS | Deep River | 249 | Poweshiek County |
| Deer Creek Subdivision (Fort Dodge) | IA9433302 | CWS | Humboldt | 55 | Webster County |
| Deer Hunters Run | IA2570304 | CWS | Ankeny | 78 | Dallas County |
| Deer Ridge Homeowners Water Assc. | IA5765303 | CWS | Cedar Rapids | 94 | Linn County |
| Deer Valley Homeowners Assoc | IA8215325 | CWS | Blue Grass | 44 | Scott County |
| Deerfield Heights Association | IA9630316 | CWS | Ossian | 28 | Winneshiek County |
| Deerwood Estates Utilities | IA9433349 | CWS | Fort Dodge | 175 | Webster County |
| Defiance Water Department | IA8315018 | CWS | Defiance | 250 | Shelby County |
| Delaware Municipal Water Supply | IA2813019 | CWS | Oelwein | 142 | Delaware County |
| Delhi Water Supply | IA2817020 | CWS | Delhi | 420 | Delaware County |
| Delmar Water Supply | IA2328024 | CWS | Maquoketa | 542 | Clinton County |
| Deloit Muni Water Supply | IA2421025 | CWS | Deloit | 250 | Crawford County |
| Delta Water Supply | IA5417026 | CWS | Sigourney | 264 | Keokuk County |
| Denver Water Supply | IA0915030 | CWS | Denver | 1,919 | Bremer County |
| Devils Creek Estates Home Assoc | IA8218301 | CWS | Davenport | 145 | Scott County |
| Dexter Water Supply | IA2533038 | CWS | Dexter | 693 | Dallas County |
| Diagonal Water Department | IA8018040 | CWS | Diagonal | 338 | Ringgold County |
| Dickens Water Works | IA2109041 | CWS | Spencer | 146 | Clay County |
| Dike Water Supply | IA3815042 | CWS | Dike | 1,306 | Grundy County |
| Dmww-Greenbrier Estates | IA7709801 | CWS | Des Moines | 300 | Dallas County |
| Dodds Valley View Water Assn | IA8209600 | CWS | Leclaire | 220 | Scott County |
| Dolliver Muni Water Supply | IA3215044 | CWS | Spencer | 65 | Emmet County |
| Donnellson Muni Water Works | IA5620046 | CWS | Donnellson | 885 | Lee County |
| Doon Water Supply | IA6015047 | CWS | Doon | 619 | Lyon County |
| Dorell Drive Home Owners Association | IA3544301 | CWS | Hampton | 32 | Franklin County |
| Dow City Water Works | IA2427049 | CWS | Dow City | 467 | Crawford County |
| Dows Water Supply | IA9921050 | CWS | Dows | 526 | Franklin County, Wright County |
| Droessler'S Water | IA4910701 | CWS | Dubuque | 158 | Emmet County |
| Dumont Water Supply | IA1240081 | CWS | Marshalltown | 635 | Butler County |
| Duncombe Water Supply | IA9427082 | CWS | Duncombe | 384 | Webster County |
| Dunkerton Muni Water Supply | IA0717084 | CWS | Dunkerton | 842 | Black Hawk County |
| Dunlap Water Supply | IA4316087 | CWS | Dunlap | 1,035 | Harrison County |
| Durant Water Supply | IA1636090 | CWS | Durant | 1,871 | Cedar County, Muscatine County, Scott County |
| Dysart Water Supply | IA8627095 | CWS | Dysart | 1,281 | Tama County |
| Eagle Lane Corporation | IA8215308 | CWS | Blue Grass | 53 | Scott County |
| Eagle Ridge | IA5751602 | CWS | Marion | 1,005 | Linn County |
| Earlham Municipal Waterworks | IA6115097 | CWS | Earlham | 1,446 | Madison County |
| Earling Water Supply | IA8320098 | CWS | Earling | 397 | Shelby County |
| Earlville Muni Water Supply | IA2825099 | CWS | Earlville | 724 | Delaware County |
| Early Municipal Water Supply | IA8114000 | CWS | Early | 587 | Sac County |
| East Side Acres | IA9700630 | CWS | Moville | 70 | Woodbury County |
| Eastern Hills Baptist Church | IA7820851 | NTNCWS | Council Bluffs | 149 | Pottawattamie County |
| Edgewood Water Supply | IA2220002 | CWS | Edgewood | 939 | Clayton County, Delaware County |
| Eip Manufacturing, Llc | IA2825101 | NTNCWS | Earlville | 60 | Delaware County |
| Elberon Water Supply | IA8631003 | CWS | Van Horne | 184 | Tama County |
| Eldon Water Supply | IA9053004 | CWS | Washington | 927 | Wapello County |
| Eldora Water Supply | IA4236005 | CWS | Eldora | 2,664 | Hardin County |
| Elgin Municipal Water Supply | IA3338010 | CWS | Elgin | 685 | Fayette County |
| Elk Horn Muni Water Works | IA8325013 | CWS | Elk Horn | 631 | Shelby County |
| Elk Run Heights Water Supply | IA0721014 | CWS | Elk Run Heights | 1,069 | Black Hawk County |
| Elkader Muni Water Dept | IA2223011 | CWS | Elkader | 1,219 | Clayton County |
| Elkhart Water Supply | IA7730012 | CWS | Ankeny | 882 | Polk County |
| Elliott Water Supply | IA6915015 | CWS | Elliott | 345 | Montgomery County |
| Ellsworth Public Water Supply | IA4009016 | CWS | Ellsworth | 514 | Hamilton County |
| Elma Water Supply | IA4525017 | CWS | Elma | 505 | Howard County |
| Ely Water Supply | IA5728018 | CWS | Ely | 2,328 | Linn County |
| Emerson Water Department | IA6520019 | CWS | Emerson | 412 | Mills County |
| Epworth Water Supply | IA3133033 | CWS | Epworth | 2,023 | Dubuque County |
| Equistar Chemicals Lp | IA2326104 | NTNCWS | Clinton | 715 | Clinton County |
| Essex Water Supply | IA7349023 | CWS | Essex | 722 | Page County |
| Everly Water Supply | IA2115029 | CWS | Everly | 575 | Clay County |
| Ewing Trace Mhc | IA7727604 | CWS | Newton | 455 | Polk County |
| Exira Water Dept | IA0520030 | CWS | Exira | 764 | Audubon County |
| Fairbank Water Supply | IA1025031 | CWS | Fairbank | 1,111 | Buchanan County, Fayette County |
| Fairfax Water Supply | IA5731032 | CWS | Fairfax | 2,828 | Linn County |
| Fairfield Estates Mobile Home Park | IA5131302 | CWS | Kansas City | 140 | Jefferson County |
| Fairview Terrrace Mobile Home Park Llc | IA5300600 | CWS | Oviedo | 72 | Jones County, Linn County |
| Far Horizons Subdivision | IA5225386 | CWS | Oxford | 80 | Johnson County |
| Farley Water Supply | IA3135018 | CWS | Farley | 1,766 | Dubuque County |
| Farmers All Natural Creamery | IA5213101 | NTNCWS | Lone Tree | 27 | Johnson County |
| Farmersburg Waterworks | IA2228037 | CWS | Monona | 276 | Clayton County |
| Farmington Water Supply | IA8930038 | CWS | Farmington | 601 | Van Buren County |
| Farnhamville Water Supply | IA1320039 | CWS | Gilmore City | 379 | Calhoun County |
| Farragut Water Supply | IA3615040 | CWS | Farragut | 490 | Fremont County |
| Fashionable Meadows | IA8222601 | CWS | Leclaire | 40 | Scott County |
| Fayette Water Supply | IA3342041 | CWS | Fayette | 1,256 | Fayette County |
| Featherlite Manufacturing, Llc. | IA4535101 | NTNCWS | Cresco | 45 | Howard County |
| Fenton Municipal Water Supply | IA5515042 | CWS | Fenton | 254 | Kossuth County |
| Fertile Municipal Water | IA9820010 | CWS | Fertile | 306 | Worth County |
| Fisher Well Owners Association | IA5285305 | CWS | Oxford | 80 | Johnson County |
| Five Star Cooperative (Scarville) | IA9580073 | NTNCWS | Manly | 114 | Winnebago County |
| Floyd Muni Water Supply | IA3414044 | CWS | Floyd | 313 | Floyd County |
| Flying J No 572 | IA4070204 | NTNCWS | Mcclure | 1,892 | Hamilton County |
| Fonda Water Supply | IA7603045 | CWS | Fonda | 636 | Pocahontas County |
| Fontanelle Water Works | IA0135046 | CWS | Fontanelle | 670 | Adair County |
| Forest Manor Subdivision | IA8209308 | CWS | Blue Grass | 209 | Scott County |
| Forestgate Subdivision | IA5225307 | CWS | Iowa City | 140 | Johnson County |
| Fort Atkinson Water Works | IA9641049 | CWS | Fort Atkinson | 347 | Winneshiek County |
| Fostoria Municipal Water Supply | IA2122067 | CWS | Spencer | 233 | Clay County |
| Four Oaks Family And Childrens Services | IA5715802 | CWS | Tipton | 50 | Linn County |
| Fox Lake Rv Park Llc | IA3621401 | NTNCWS | Omaha | 75 | Fremont County |
| Fox Valley Acres | IA7048319 | CWS | Muscatine | 36 | Muscatine County |
| Frankville Rwd | IA9644001 | CWS | Ossian | 135 | Fayette County, Winneshiek County |
| Fredericksburg Water Supply | IA1940068 | CWS | Fredericksburg | 987 | Chickasaw County |
| Freeport Water District | IA9630001 | CWS | Decorah | 775 | Winneshiek County |
| Frontier Village | IA9433602 | CWS | Homestead | 108 | Webster County |
| Frytown Water Coop | IA5291301 | CWS | Kalona | 87 | Johnson County |
| Gaddis Estates Hoa | IA5731302 | CWS | Oxford | 220 | Linn County |
| Gallery Acres West | IA5282306 | CWS | Tipton | 43 | Johnson County |
| Galva Water Supply | IA4715072 | CWS | Galva | 435 | Ida County |
| Garnavillo Water Supply | IA2234074 | CWS | Garnavillo | 763 | Clayton County |
| Garner Water Works | IA4130075 | CWS | Garner | 3,065 | Hancock County |
| Garrison Water Supply | IA0625078 | CWS | Traer | 344 | Benton County |
| Garwin Water Supply | IA8637079 | CWS | Garwin | 481 | Tama County |
| Gateway Development | IA5225312 | NTNCWS | Tipton | 400 | Johnson County |
| Gavin Estates | IA3100823 | CWS | Dubuque | 52 | Dubuque County |
| Geneva Water Works | IA3539080 | CWS | Geneva | 136 | Franklin County |
| George Water Supply | IA6028081 | CWS | George | 1,082 | Lyon County |
| Gilbert Water Supply | IA8531083 | CWS | Gilbert | 1,211 | Story County |
| Gilbertville Water Works | IA0733084 | CWS | Gilbertville | 796 | Black Hawk County |
| Gilman Water Supply | IA6436087 | CWS | Newton | 582 | Marshall County |
| Gilmore City Waterworks | IA7607088 | CWS | Gilmore City | 487 | Humboldt County, Pocahontas County |
| Gladbrook Water Supply | IA8640089 | CWS | Gladbrook | 799 | Tama County |
| Glenbrook Cove Area | IA5751040 | CWS | Marion | 233 | Linn County |
| Glenn Oaks Addition | IA5784313 | CWS | Cedar Rapids | 58 | Linn County |
| Glidden Water Supply | IA1438091 | CWS | Glidden | 1,140 | Carroll County |
| Goldfield Water Supply | IA9937092 | CWS | Goldfield | 634 | Wright County |
| Goodell Water Supply | IA4135093 | CWS | Goodell | 140 | Hancock County |
| Goose Lake Muni Water System | IA2339094 | CWS | Goose Lake | 239 | Clinton County |
| Gowrie Muni Utilities Water Dept | IA9436095 | CWS | Gowrie | 954 | Webster County |
| Graettinger Municipal Water Supply | IA7445096 | CWS | Graettinger | 897 | Palo Alto County |
| Grafton Water Supply | IA9825097 | CWS | Grafton | 218 | Worth County |
| Grand Jct Municipal Water Dept | IA3730098 | CWS | Grand Junction | 725 | Greene County |
| Grand Mound Water Supply | IA2341099 | CWS | Grand Mound | 615 | Clinton County |
| Grandview Muni Water Dept | IA5842000 | CWS | Grandview | 437 | Louisa County |
| Granger Muni Water Supply | IA2537001 | CWS | Granger | 1,654 | Dallas County, Polk County |
| Granville Water Supply | IA8429002 | CWS | Granville | 310 | Sioux County |
| Green Acres Mobile Home Park | IA2900603 | CWS | Burlington | 190 | Des Moines County |
| Green Brier Subdivision | IA3126307 | CWS | Dubuque | 35 | Dubuque County |
| Greene Muni Water Supply | IA1253006 | CWS | Greene | 994 | Butler County |
| Greenfield Municipal Utilities | IA0140007 | CWS | Greenfield | 2,227 | Adair County |
| Greenwood Acres Water Co. | IA7709395 | CWS | Ankeny | 325 | Polk County |
| Grimes Mhp | IA7736601 | CWS | Homestead | 163 | Polk County |
| Grinnell Mhp Mhc | IA7930601 | CWS | Homestead | 313 | Poweshiek County |
| Griswold Water Supply | IA1528010 | CWS | Griswold | 1,008 | Cass County |
| Grundy Center Water Supply | IA3833013 | CWS | Grundy Center | 2,796 | Grundy County |
| Guthrie Center Muni Water Work | IA3937016 | CWS | Guthrie Center | 1,593 | Guthrie County |
| Guttenberg Water Utility | IA2242018 | CWS | Guttenberg | 1,817 | Clayton County |
| Halbur Water Supply | IA1444022 | CWS | Halbur | 249 | Carroll County |
| Hamburg Water Supply | IA3621023 | CWS | Hamburg | 890 | Fremont County |
| Hammond Estates | IA8580601 | CWS | Madrid | 150 | Story County |
| Hancock Water Supply | IA7833025 | CWS | Hancock | 200 | Pottawattamie County |
| Hanlontown Water Supply System | IA9830001 | CWS | Hanlontown | 206 | Worth County |
| Hansell Water Department | IA3549026 | CWS | Hansell | 82 | Franklin County |
| Harcourt Water Supply | IA9442027 | CWS | Fort Dodge | 265 | Webster County |
| Harper Water Supply | IA5428031 | CWS | Muscatine | 118 | Keokuk County |
| Harris Water Supply | IA7222034 | CWS | Sibley | 151 | Osceola County |
| Hartford Mhc Llc | IA9128301 | CWS | Knoxville | 183 | Warren County |
| Hartley Municipal Water Department | IA7128036 | CWS | Hartley | 1,605 | O'Brien County |
| Hastings Water Supply | IA6527038 | CWS | Marshalltown | 152 | Mills County |
| Havelock Water Supply | IA7609039 | CWS | Whittemore | 130 | Pocahontas County |
| Hawarden Water Supply | IA8434040 | CWS | Hawarden | 2,700 | Sioux County |
| Hawkeye Pride Egg Farm Llp | IA4109101 | NTNCWS | Storm Lake | 100 | Hancock County |
| Hawkeye Ready-Mix (Coralville) | IA5208103 | NTNCWS | Coralville | 26 | Johnson County |
| Hawkeye Water Supply | IA3346037 | CWS | Hawkeye | 438 | Fayette County |
| Hazleton Mobile Home Park | IA1031601 | CWS | Hazleton | 150 | Buchanan County |
| Hazleton Water Supply | IA1031044 | CWS | Jesup | 713 | Buchanan County |
| Hedrick Water Supply | IA5432042 | CWS | Hedrick | 728 | Keokuk County |
| Heidelberg Materials Us Cement Llc | IA1750196 | NTNCWS | Mason City | 130 | Cerro Gordo County |
| Henderson Water Department | IA6529043 | CWS | Carson | 144 | Mills County |
| Henning Commercial Subdivision | IA9630209 | NTNCWS | Decorah | 40 | Winneshiek County |
| Hickory Acres | IA3126304 | CWS | Marshalltown | 115 | Dubuque County |
| Hickory Hills First Annex Hoa | IA8215372 | CWS | Blue Grass | 156 | Scott County |
| Hickory Hills Second Annex | IA8215373 | CWS | Blue Grass | 130 | Scott County |
| Hickory Hills Subdivision #1 | IA8215302 | CWS | Davenport | 75 | Scott County |
| Hickory Hills Subdivision #2 | IA8215303 | CWS | Davenport | 181 | Scott County |
| Hickory Hollow Water Service, Inc. | IA7709396 | CWS | Ankeny | 375 | Polk County |
| Hidden Acres Subdivision | IA5282308 | CWS | Solon | 90 | Johnson County |
| Highland High School | IA9260528 | NTNCWS | Muscatine | 405 | Washington County |
| Hillandale Iowa Ii Llp | IA3383101 | NTNCWS | West Union | 35 | Fayette County |
| Hillcrest Academy | IA9233520 | NTNCWS | Kalona | 202 | Johnson County, Washington County |
| Hillock Estates | IA7727608 | CWS | Knoxville | 228 | Polk County |
| Hills Water Supply | IA5221001 | CWS | Hills | 863 | Johnson County |
| Hillsboro Water Works | IA4425032 | CWS | Washington | 163 | Henry County |
| Hilltop Farms #3Rd Addition | IA7048320 | CWS | Muscatine | 26 | Muscatine County |
| Hilltop Road Association #1 | IA7048392 | CWS | Muscatine | 45 | Muscatine County |
| Hilltop Road Association #2 | IA7048308 | CWS | Muscatine | 55 | Muscatine County |
| Hilltop Village Mhc, Inc. | IA1800601 | CWS | Newell | 78 | Cherokee County |
| Hinton Water Supply | IA7528051 | CWS | Hinton | 935 | Plymouth County |
| Holland Water Supply | IA3839052 | CWS | Newton | 270 | Grundy County |
| Holstein, City Of | IA4721054 | CWS | Holstein | 1,511 | Ida County |
| Holy Cross Water Supply | IA3146055 | CWS | Holy Cross | 356 | Dubuque County |
| Homeland Energy Solution Llc | IA1970801 | NTNCWS | Lawler | 60 | Chickasaw County |
| Hopkinton Municipal Utilities | IA2835056 | CWS | Hopkinton | 622 | Delaware County |
| Hornick Water Supply | IA9738057 | CWS | Hornick | 255 | Woodbury County |
| Hospers Municipal Water Dept | IA8439058 | CWS | Marshalltown | 718 | Sioux County |
| Hubbard Water Supply | IA4254061 | CWS | Hubbard | 860 | Hardin County |
| Hudson Water Supply | IA0737062 | CWS | Hudson | 2,546 | Black Hawk County |
| Hull Water Supply | IA8444063 | CWS | Hull | 2,384 | Sioux County |
| Humeston Water Plant | IA9348065 | CWS | Humeston | 465 | Wayne County |
| Hwh Corporation | IA1672101 | NTNCWS | Moscow | 250 | Cedar County |
| Hwh Corporation (West) | IA7078101 | NTNCWS | Moscow | 50 | Cedar County |
| Ida Grove Water Utility | IA4728067 | CWS | Ida Grove | 2,051 | Ida County |
| Ila Campus Llc | IA5159301 | CWS | Muscatine | 68 | Jefferson County |
| Indian Hills Home Owners Association | IA5280302 | CWS | Solon | 62 | Johnson County |
| Indian Ridge Mobile Home Community | IA9133602 | CWS | Indianola | 153 | Warren County |
| Inwood Water Supply | IA6040076 | CWS | Inwood | 928 | Lyon County |
| Ionia Water Supply | IA1946078 | CWS | Riceville | 226 | Chickasaw County |
| Iowa American Water Donahue | IA8227045 | CWS | Davenport | 335 | Scott County |
| Iowa Army Ammunition Plant | IA2900900 | NTNCWS | Middletown | 1,100 | Des Moines County |
| Iowa Cage Free | IA9937101 | NTNCWS | Goldfield | 45 | Wright County |
| Iowa Cage Free - Thompson | IA9585801 | NTNCWS | Thompson | 170 | Winnebago County |
| Iowa City Regency Mobile Home Community | IA5225673 | CWS | Iowa City | 225 | Johnson County |
| Iowa Contract Fabricators Inc | IA4558101 | NTNCWS | Riceville | 160 | Howard County |
| Iowa Limestone Co | IA4213103 | NTNCWS | Alden | 48 | Hardin County |
| Iowa Valley Estates | IA4800634 | CWS | Marengo | 46 | Iowa County |
| Iowa-American Water (Low Moor) | IA2348002 | CWS | Clinton | 250 | Clinton County |
| Iowa-American Water-Dixon | IA8225043 | CWS | Davenport | 204 | Scott County |
| Ireton Water Supply | IA8447098 | CWS | Ireton | 590 | Sioux County |
| Irua (Dows) | IA3564901 | NTNCWS | Newton | 2,042 | Franklin County |
| Irua - Pershing Utilities | IA6300800 | CWS | Newton | 488 | Jasper County, Marion County |
| Irwin Municipal Supply | IA8340099 | CWS | Irwin | 313 | Shelby County |
| Jacobs Landing Hoa | IA5280306 | CWS | Muscatine | 84 | Johnson County |
| Jamaica Water Supply | IA3949000 | CWS | Jamaica | 195 | Guthrie County |
| Janesville Water Supply | IA0932001 | CWS | Janesville | 1,034 | Bremer County |
| Jefferson County Rural Water District | IA5131705 | CWS | Fairfield | 468 | Jefferson County |
| Jesup Municipal Water Supply | IA1044006 | CWS | Jesup | 2,508 | Black Hawk County, Buchanan County |
| Jewell Water Supply | IA4027010 | CWS | Jewell | 1,216 | Hamilton County |
| John Deere Dubuque Works | IA3126116 | NTNCWS | Dubuque | 3,000 | Dubuque County |
| Joice Water Supply | IA9835001 | CWS | Lake Mills | 208 | Worth County |
| Jolley Water Supply | IA1335001 | CWS | Pocahontas | 28 | Calhoun County |
| Kalona Water Dept | IA9233012 | CWS | Kalona | 2,630 | Washington County |
| Kammerer Mobile Home Park | IA7000686 | CWS | New Port Beach | 100 | Muscatine County |
| Kanawha Water Supply | IA4150014 | CWS | Kanawha | 658 | Hancock County |
| Kauths Oak Valley Hoa 2Nd Addition | IA8218303 | CWS | Buffalo | 31 | Scott County |
| Kellerton Water Supply | IA8040015 | CWS | Mount Ayr | 247 | Ringgold County |
| Kelley Water Supply | IA8548016 | CWS | Madrid | 304 | Story County |
| Kellogg Water Supply | IA5038017 | CWS | Kellogg | 617 | Jasper County |
| Kensett Water Supply | IA9840018 | CWS | Kensett | 257 | Worth County |
| Keosauqua Water Works | IA8938026 | CWS | Keosauqua | 961 | Van Buren County |
| Keota Water Dept | IA5440028 | CWS | Muscatine | 897 | Keokuk County |
| Kesslers Homeowners Assn | IA5200802 | CWS | Iowa City | 60 | Johnson County |
| Keswick Water System | IA5442029 | CWS | South English | 252 | Keokuk County |
| Keystone Water Supply | IA0640030 | CWS | Keystone | 599 | Benton County |
| Kimballton Utilities | IA0543031 | CWS | Kimballton | 287 | Audubon County |
| Kingsley Water Supply | IA7537032 | CWS | Kingsley | 1,396 | Plymouth County |
| Kinze Manufacturing Inc | IA4884101 | NTNCWS | Williamsburg | 710 | Iowa County |
| Kiron Water Supply | IA2432034 | CWS | Kiron | 257 | Crawford County |
| Klemme Water Works | IA4155035 | CWS | Klemme | 441 | Hancock County |
| Knierim Water Supply | IA1340001 | CWS | Fort Dodge | 53 | Calhoun County |
| Knollcrest Hoa | IA8222301 | CWS | Leclaire | 42 | Scott County |
| Kol Gol Inc | IA0398102 | NTNCWS | Waukon | 42 | Allamakee County |
| Kurth Addition | IA5784319 | CWS | Cedar Rapids | 33 | Linn County |
| La Motte Water Supply | IA4945052 | CWS | Marshalltown | 237 | Jackson County |
| La Porte City Utilities | IA0743057 | CWS | Laporte City | 2,284 | Black Hawk County |
| Lacona Water Supply | IA9138041 | CWS | Lacona | 361 | Warren County |
| Ladora Water Supply | IA4840042 | CWS | Belle Plaine | 229 | Iowa County |
| Lake City Water Supply | IA1345043 | CWS | Lake City | 1,731 | Calhoun County |
| Lake Creek Homeowners Association | IA1178800 | CWS | Storm Lake | 175 | Buena Vista County |
| Lake Crest Manor Hoa #3 | IA5200891 | CWS | Solon | 300 | Johnson County |
| Lake Huntington Estates | IA8230302 | CWS | Davenport | 102 | Scott County |
| Lake Macbride Heights Hoa | IA5282305 | CWS | Oxford | 69 | Johnson County |
| Lake Mills Municipal Water Dept-South | IA9545044 | CWS | Lake Mills | 2,158 | Winnebago County |
| Lake Panorama Water Company | IA3900301 | CWS | Panora | 2,900 | Guthrie County |
| Lake Park Municipal Utilities | IA3045046 | CWS | Lake Park | 1,167 | Dickinson County |
| Lake Ridge, Incorporated | IA5225315 | CWS | Grinnell | 1,300 | Johnson County |
| Lake View Water Supply | IA8127048 | CWS | Lake View | 1,133 | Sac County |
| Lake Vista Subdivision | IA5282302 | CWS | Swisher | 134 | Johnson County |
| Lake Woods Hoa | IA5280305 | CWS | Muscatine | 114 | Johnson County |
| Lakeside Estates Llc | IA7812601 | CWS | Council Bluffs | 823 | Pottawattamie County |
| Lakeside Water Supply | IA1145047 | CWS | Lakeside | 700 | Buena Vista County |
| Lakeview Knolls Homeowners Assn. | IA5200304 | CWS | Solon | 122 | Johnson County |
| Lakewood Utilities | IA9433324 | CWS | Fort Dodge | 135 | Webster County |
| Lakota Water Supply | IA5540049 | CWS | Gilmore City | 267 | Kossuth County |
| Lamoni Municipal Utilities | IA2740050 | CWS | Lamoni | 2,029 | Decatur County |
| Lamont Water Supply | IA1051051 | CWS | Lamont | 429 | Buchanan County |
| Lanesboro Water Works | IA1449053 | CWS | Fort Dodge | 119 | Carroll County |
| Lansing Water Supply | IA0345054 | CWS | Lansing | 983 | Allamakee County |
| Larchwood Water Supply | IA6050059 | CWS | Larchwood | 926 | Lyon County |
| Larrabee Municipal Water Works | IA1833060 | CWS | Storm Lake | 125 | Cherokee County |
| Latimer Water Supply | IA3554061 | CWS | Hampton | 477 | Franklin County |
| Laurel Municipal Water Works | IA6452062 | CWS | Laurel | 220 | Marshall County |
| Laurens Water Supply | IA7614063 | CWS | Laurens | 1,301 | Pocahontas County |
| Lawler Water Supply | IA1957064 | CWS | Lawler | 406 | Chickasaw County |
| Lawton Water Supply | IA9743065 | CWS | Lawton | 988 | Woodbury County |
| Le Grand Water Works | IA6457070 | CWS | Legrand | 910 | Marshall County |
| Leaf Lake Estates Hoa | IA8218302 | CWS | Davenport | 53 | Scott County |
| Ledyard Water Supply | IA5543069 | CWS | Whittemore | 121 | Kossuth County |
| Lehigh Water Supply | IA9453071 | CWS | Fort Dodge | 395 | Webster County |
| Leisure Living Manf Home Community | IA9083602 | CWS | Ottumwa | 150 | Wapello County |
| Leland Water Supply | IA9549073 | CWS | Thompson | 249 | Winnebago County |
| Lemar Industries | IA3570101 | NTNCWS | Sheffield | 45 | Franklin County |
| Lenox Water Supply | IA8748075 | CWS | Lenox | 1,470 | Taylor County |
| Lenwood Utilities | IA0717353 | CWS | Cedar Falls | 238 | Black Hawk County |
| Leon Water Supply | IA2742076 | CWS | Leon | 1,830 | Decatur County |
| Lester Water Supply | IA6055077 | CWS | Lester | 296 | Lyon County |
| Lewis And Clark Regional Water System | IA8486701 | CWS | Vermillion | 25 | Sioux County |
| Lewis Water Supply | IA1535078 | CWS | Lewis | 357 | Cass County |
| Libertyville Water Works | IA5148079 | CWS | Batavia | 304 | Jefferson County |
| Lidderdale Water Supply | IA1453080 | CWS | Lidderdale | 166 | Carroll County |
| Lime Springs Water Supply | IA4535081 | CWS | Riceville | 473 | Howard County |
| Lindsey Estates | IA5285301 | CWS | Oxford | 62 | Johnson County |
| Lineville Water Supply | IA9352084 | CWS | Lineville | 250 | Wayne County |
| Linn Grove Water Works | IA1147085 | CWS | Linn Grove | 163 | Buena Vista County |
| Linn Hollow Mhp Llc | IA9200601 | CWS | Muscatine | 68 | Washington County |
| Linwood Mining And Minerals Corp | IA8222101 | NTNCWS | Davenport | 125 | Scott County |
| Lisbon Water Supply | IA5748086 | CWS | Lisbon | 2,233 | Linn County |
| Liscomb Water Supply | IA6462087 | CWS | Newton | 291 | Marshall County |
| Little Angels Child Care Center | IA5285501 | NTNCWS | Swisher | 65 | Johnson County |
| Little Bear Campground | IA1677601 | CWS | Tipton | 45 | Cedar County |
| Little Rock Water Supply | IA6060006 | CWS | Little Rock | 441 | Lyon County |
| Little Sioux Water Department | IA4333089 | CWS | Little Sioux | 150 | Harrison County |
| Livermore Water Supply | IA4647090 | CWS | Livermore | 383 | Humboldt County |
| Lizard Creek Ranch | IA9433801 | CWS | Fort Dodge | 125 | Webster County |
| Lockridge Muni Water Supply | IA5157091 | CWS | Washington | 244 | Jefferson County |
| Logan Water Supply | IA4337092 | CWS | Logan | 1,397 | Harrison County |
| Logansport Water System | IA0837701 | CWS | Ames | 190 | Boone County |
| Lohrville Water Supply | IA1389001 | CWS | Newell | 381 | Calhoun County |
| Lone Rock Water Supply | IA5547094 | CWS | Whittemore | 146 | Kossuth County |
| Lone Tree Muni Water System | IA5240095 | CWS | Muscatine | 1,357 | Johnson County |
| Long Beach Mobile Park | IA1700642 | CWS | Clear Lake | 50 | Cerro Gordo County |
| Long Grove Muni Water Supply | IA8251096 | CWS | Long Grove | 838 | Scott County |
| Longview Estates Hoa (North Liberty) | IA5252302 | CWS | Oxford | 108 | Johnson County |
| Lore Mound Mobile Home Park | IA3100601 | CWS | Peosta | 68 | Dubuque County |
| Lore Oaks Homeowners Assn. | IA3126306 | CWS | Dubuque | 64 | Dubuque County |
| Lost Canyon Mhp (Peosta) | IA3100608 | CWS | Peosta | 97 | Dubuque County |
| Lost Nation Water Supply | IA2346047 | CWS | Lost Nation | 434 | Clinton County |
| Louisa Co Law Enforcement Ctr | IA5800901 | CWS | Muscatine | 46 | Louisa County |
| Louisa Courts Mhp & Sales | IA7000689 | CWS | Muscatine | 121 | Muscatine County |
| Louisa Generating Station Ws 2 | IA5842102 | NTNCWS | Muscatine | 100 | Louisa County, Muscatine County |
| Louisa-Muscatine Community School | IA5847537 | NTNCWS | Letts | 1,190 | Louisa County |
| Lovilia Municipal Water Department | IA6858000 | CWS | Lovilia | 472 | Monroe County |
| Lowden Water Supply | IA1656001 | CWS | Lowden | 807 | Cedar County |
| Lu Verne Water Supply | IA5551006 | CWS | Lu Verne | 258 | Humboldt County, Kossuth County |
| Luana Water Works | IA2254061 | CWS | Luana | 301 | Clayton County |
| Luxemburg Water Supply | IA3158001 | CWS | Luxemburg | 245 | Dubuque County |
| Lyn-Den Heights Homeowners Assoc. | IA5225301 | CWS | Oxford | 84 | Johnson County |
| Lynnville Water Dept | IA5047008 | CWS | Lynnville | 380 | Jasper County |
| Lyon-Sioux Rws-Boyden | IA6000744 | CWS | Rock Rapids | 605 | Lyon County |
| Lyon-Sioux Rws-Doon | IA6000733 | CWS | Rock Rapids | 1,765 | Lyon County |
| Lyon-Sioux Rws-Rock Rapids | IA6000800 | CWS | Rock Rapids | 1,187 | Lyon County |
| Lytton Water Department | IA8133009 | CWS | Lytton | 282 | Calhoun County, Sac County |
| Macbride Estates Development | IA5282310 | CWS | Solon | 63 | Johnson County |
| Macedonia Water Supply | IA7841014 | CWS | Macedonia | 275 | Pottawattamie County |
| Madrid Water Department | IA0848015 | CWS | Perry | 3,090 | Boone County |
| Magnolia, City Of | IA4341017 | CWS | Magnolia | 188 | Harrison County |
| Maharishi Vedic City Water Supply | IA5159001 | CWS | Maharishi Vedic City | 60 | Jefferson County |
| Mahaska Rural Water (New Sharon) | IA6264063 | CWS | Oskaloosa | 1,368 | Mahaska County |
| Makada Homeowners Association | IA5225304 | CWS | Iowa City | 85 | Johnson County |
| Malcom Water Supply | IA7945018 | CWS | Malcom | 270 | Poweshiek County |
| Mallard Water Supply | IA7450019 | CWS | Mallard | 257 | Palo Alto County |
| Malvern Water Supply | IA6545020 | CWS | Malvern | 1,046 | Mills County |
| Manilla Muni Service Dept | IA2436023 | CWS | Manilla | 758 | Crawford County |
| Manly Water Supply | IA9845024 | CWS | Manly | 1,266 | Worth County |
| Manning Water Supply | IA1457025 | CWS | Manning | 1,392 | Carroll County |
| Manson Water Supply | IA1351027 | CWS | Manson | 1,727 | Calhoun County |
| Maple Grove Mhc | IA0800601 | CWS | Madrid | 160 | Boone County, Story County |
| Mapleton Municipal Water Plant | IA6727028 | CWS | Mapleton | 1,124 | Monona County |
| Marathon Light & Water Department | IA1150030 | CWS | Marathon | 230 | Buena Vista County |
| Marble Rock Water Supply | IA3420031 | CWS | Marble Rock | 272 | Floyd County |
| Marcus Water Supply | IA1838032 | CWS | Marcus | 1,079 | Cherokee County |
| Marengo Water Supply | IA4843033 | CWS | Marengo | 2,435 | Iowa County |
| Marion Co Rwd (Harvey) | IA6338000 | CWS | Knoxville | 236 | Marion County |
| Marion Village | IA5751601 | CWS | Newton | 850 | Linn County |
| Mark Twain Meadows Homeowners | IA7048301 | CWS | Muscatine | 375 | Muscatine County |
| Marquette Water Supply | IA2256041 | CWS | Marquette | 429 | Clayton County |
| Marshalltown Estates | IA6400628 | CWS | Marshalltown | 382 | Marshall County |
| Martelle Water Works | IA5337046 | CWS | Cedar Rapids | 249 | Jones County |
| Martensdale Water Supply | IA9147047 | CWS | Martensdale | 421 | Warren County |
| Massena Water Supply | IA1558055 | CWS | Massena | 364 | Cass County |
| Matlock Water Supply | IA8455056 | CWS | Matlock | 74 | Sioux County |
| Maurice Municipal Water Supply | IA8458057 | CWS | Maurice | 265 | Sioux County |
| Maxwell Water Department | IA8557058 | CWS | Maxwell | 859 | Story County |
| Maynard Water Supply | IA3350059 | CWS | Maynard | 476 | Fayette County |
| Maysville Municipal Water Dept | IA8255060 | CWS | Calamus | 156 | Scott County |
| Mcbride Pointe Third Master Maintenance | IA5282311 | CWS | Oxford | 25 | Johnson County |
| Mccallsburg Water Supply | IA8552010 | CWS | Colo | 353 | Story County |
| Mccarty Creek Homeowners Assn #8 | IA8245323 | CWS | Leclaire | 85 | Scott County |
| Mcgregor Water Dept | IA2258012 | CWS | Mcgregor | 747 | Clayton County |
| Meadow Knolls Addition | IA5751301 | CWS | Dewitt | 53 | Linn County |
| Meadow Lane Mobile Home Park | IA0900647 | CWS | Jesup | 168 | Bremer County |
| Mecha Ceba Water System Association | IA7000617 | CWS | Muscatine | 87 | Muscatine County |
| Mechanicsville Water Dept | IA1667076 | CWS | Mechanicsville | 1,020 | Cedar County |
| Mediapolis Village Court | IA2948601 | CWS | Kansas City | 100 | Des Moines County |
| Mediapolis Water Supply | IA2948062 | CWS | Mediapolis | 1,688 | Des Moines County |
| Melbourne Water Supply | IA6471063 | CWS | Melbourne | 765 | Marshall County |
| Melvin Waterworks | IA7234069 | CWS | Sibley | 202 | Osceola County |
| Meriden Municipal Water Supply | IA1849071 | CWS | Storm Lake | 161 | Cherokee County |
| Merrill Municipal Water Supply | IA7548072 | CWS | Merrill | 717 | Plymouth County |
| Meservey Water Supply | IA1754073 | CWS | Manly | 222 | Cerro Gordo County |
| Michael Foods - Britt | IA4103101 | NTNCWS | Britt | 110 | Hancock County |
| Mid-Prairie Home School Ed Center | IA9233522 | NTNCWS | Kalona | 160 | Johnson County, Washington County |
| Midamerican Energy Co - Neal South | IA9778106 | NTNCWS | Sioux City | 107 | Woodbury County |
| Midamerican Energy Co. Neal North | IA9778105 | NTNCWS | Sioux City | 100 | Woodbury County |
| Middletown Water Supply | IA2952075 | CWS | Middletown | 336 | Des Moines County |
| Midway Water And Lighting | IA5784302 | CWS | Hiawatha | 72 | Linn County |
| Midwest Country Estates | IA2573301 | CWS | Newton | 820 | Dallas County, Polk County |
| Miles Water Department | IA4953078 | CWS | Miles | 408 | Jackson County |
| Milford Municipal Utilities | IA3050079 | CWS | Milford | 3,431 | Dickinson County |
| Millersburg Water Dept | IA4852082 | CWS | Millersburg | 135 | Iowa County |
| Milo Public Water Supply | IA9155083 | CWS | Milo | 788 | Warren County |
| Milton Water Supply | IA8954084 | CWS | Milton | 380 | Van Buren County |
| Minburn Waterworks | IA2547085 | CWS | Bouton | 325 | Dallas County |
| Minden Water Supply | IA7849086 | CWS | Neola | 598 | Pottawattamie County |
| Mingo Water Department | IA5052087 | CWS | Mingo | 316 | Jasper County |
| Missouri Valley Water Supply | IA4344088 | CWS | Missouri Valley | 2,678 | Harrison County |
| Mitchellville Water Supply | IA7751092 | CWS | Mitchellville | 2,515 | Polk County |
| Modale Water Supply | IA4347093 | CWS | Logan | 280 | Harrison County |
| Modern Manor, Inc | IA5225601 | CWS | Grinnell | 915 | Johnson County |
| Mondamin Water Supply | IA4349094 | CWS | Marshalltown | 339 | Harrison County |
| Monmouth Water Supply | IA4955001 | CWS | Monmouth | 129 | Jackson County |
| Monona Municipal Water Dept | IA2264095 | CWS | Monona | 1,471 | Clayton County |
| Monroe Water Supply | IA5054096 | CWS | Monroe | 2,007 | Jasper County |
| Montezuma Muni Water Supply | IA7950097 | CWS | Montezuma | 1,545 | Poweshiek County |
| Montipark Llc | IA5300688 | CWS | Seattle | 60 | Jones County |
| Montour Water Supply | IA8666002 | CWS | Montour | 203 | Tama County |
| Montrose Water Works | IA5650003 | CWS | Montrose | 738 | Lee County |
| Moorhead Water Supply | IA6731006 | CWS | Moorhead | 189 | Monona County |
| Moorland Water Supply | IA9461007 | CWS | Fort Dodge | 168 | Webster County |
| Moravia Public Water Supply | IA0467008 | CWS | Moravia | 637 | Appanoose County |
| Morley Municipal Water Supply | IA5349001 | CWS | Anamosa | 98 | Jones County |
| Morning Sun Water Department | IA5857011 | CWS | Morning Sun | 752 | Louisa County |
| Moulton Water Department | IA0472012 | CWS | Moulton | 607 | Appanoose County |
| Mount Auburn Water Supply | IA0650001 | CWS | Vinton | 162 | Benton County |
| Mount Ayr Water Treatment Plant | IA8055014 | CWS | Mount Ayr | 1,683 | Ringgold County |
| Moville Water Supply | IA9753022 | CWS | Moville | 1,687 | Woodbury County |
| Mt Joy Mobile Home Park | IA8222603 | CWS | Eldridge | 140 | Scott County |
| Murphy Family Farms - Feed Mill | IA5502801 | NTNCWS | Humboldt | 46 | Kossuth County |
| Murray Water Works | IA2032023 | CWS | Murray | 684 | Clarke County |
| Muscatine Mhp Llc | IA7000601 | CWS | Los Angeles | 245 | Muscatine County |
| Mystic Water Supply | IA0477040 | CWS | Mystic | 322 | Appanoose County |
| Nashua Water Supply | IA1967041 | CWS | Nashua | 1,551 | Chickasaw County |
| Neola Light & Water | IA7853043 | CWS | Adair | 906 | Pottawattamie County |
| New Albin Water Supply | IA0370047 | CWS | New Albin | 432 | Allamakee County |
| New Cooperative Rowan Mill | IA9958101 | NTNCWS | Rowan | 33 | Franklin County |
| New Cooperative, Inc (Roelyn) | IA9475101 | NTNCWS | Moorland | 80 | Webster County |
| New Hartford Water Supply | IA1271058 | CWS | Marshalltown | 570 | Butler County |
| New Horizon Coop/Opal Foods - Britt | IA4103801 | NTNCWS | Britt | 30 | Hancock County |
| New Horizons Mhp Llc | IA8538601 | CWS | Newton | 303 | Story County |
| New Liberty Water Supply | IA8264059 | CWS | Long Grove | 138 | Scott County |
| New London Munic Water Dept | IA4458060 | CWS | New London | 1,910 | Henry County |
| New Market Water Supply | IA8758061 | CWS | New Market | 385 | Taylor County |
| New Providence Water Supply | IA4271062 | CWS | Newton | 236 | Hardin County |
| New Vienna Water Supply | IA3165014 | CWS | New Vienna | 382 | Dubuque County |
| New Virginia Water Supply | IA9159067 | CWS | Newton | 498 | Warren County |
| Newell Water Treatment Plant | IA1155049 | CWS | Newell | 921 | Buena Vista County |
| Newhall Water Supply | IA0653050 | CWS | Van Horne | 881 | Benton County |
| Nora Springs Water Supply | IA3423069 | CWS | Manly | 1,369 | Floyd County |
| North American Mobile Home Park | IA9133601 | CWS | De Soto | 235 | Warren County |
| North Coralville Lake Manor | IA5200889 | CWS | Solon | 55 | Johnson County |
| North End Mobile Home Park | IA3100609 | CWS | Dubuque | 40 | Dubuque County |
| North English Water Department | IA4858070 | CWS | North English | 1,065 | Iowa County |
| North Fayette Valley Community School | IA3338500 | NTNCWS | Elgin | 552 | Fayette County |
| North Linn High School / Middle School | IA5722532 | NTNCWS | Troy Mills | 724 | Linn County |
| North Twin View Heights | IA5200813 | CWS | Solon | 180 | Johnson County |
| North Union Elementary School | IA5515527 | NTNCWS | Fenton | 172 | Kossuth County |
| Northwood Estates | IA5225308 | CWS | Tipton | 52 | Johnson County |
| Northwood Waterworks | IA9855077 | CWS | Northwood | 2,072 | Worth County |
| Norway City Water Supply | IA0656081 | CWS | Muscatine | 466 | Benton County |
| Oak Creek Mhp | IA6273601 | CWS | Oskaloosa | 165 | Mahaska County |
| Oak Lake Maintenance, Inc. | IA5500838 | CWS | Whittemore | 128 | Kossuth County |
| Oak Ridge Lake Estates | IA5225302 | CWS | Cedar Rapids | 88 | Johnson County |
| Oak Shores | IA3203301 | CWS | Whittemore | 55 | Emmet County, Kossuth County |
| Oak Valley | IA5784311 | CWS | Cedar Rapids | 100 | Linn County |
| Oakdale Hospital Water System | IA5200982 | NTNCWS | Iowa City | 450 | Johnson County |
| Oakland Munic Water Utility | IA7856084 | CWS | Oakland | 1,524 | Pottawattamie County |
| Oakville Water Supply | IA5868085 | CWS | Oakville | 200 | Louisa County |
| Oakwood Park Water Inc. | IA7709398 | CWS | Ankeny | 218 | Polk County |
| Ocheyedan Water Works | IA7239086 | CWS | Ocheyedan | 439 | Osceola County |
| Odebolt Water Supply | IA8144087 | CWS | Odebolt | 994 | Sac County |
| Ogden Municipal Utilities | IA0858090 | CWS | Ogden | 2,419 | Boone County |
| Olds Municipal Water Dept | IA4465093 | CWS | Olds | 192 | Henry County |
| Olin Water Supply | IA5355094 | CWS | Wyoming | 651 | Jones County |
| Onslow Water Supply | IA5358096 | CWS | Wyoming | 201 | Jones County |
| Orchard Heights Subdivision | IA5285303 | CWS | Oxford | 78 | Johnson County |
| Orchard View Estates | IA5282304 | CWS | Tipton | 78 | Johnson County |
| Orchard Water Works | IA6668001 | CWS | Manly | 68 | Mitchell County |
| Orient Municipal Water Supply | IA0160099 | CWS | Orient | 368 | Adair County |
| Osceola Rural Water System-South | IA7177701 | CWS | May City | 2,112 | Osceola County |
| Ossian Water Supply | IA9677007 | CWS | Ossian | 802 | Winneshiek County |
| Otho Water Supply | IA9464008 | CWS | Fort Dodge | 431 | Webster County |
| Oto Water Supply | IA9758023 | CWS | Oto | 72 | Woodbury County |
| Ottosen Water Supply | IA4652011 | CWS | Whittemore | 41 | Humboldt County |
| Oxford Junction Water Supply | IA5361020 | CWS | Oxford Junction | 424 | Jones County |
| Oxford Water Supply | IA5260017 | CWS | Oxford | 722 | Johnson County |
| Oyens Water Supply | IA7561021 | CWS | Remsen | 92 | Plymouth County |
| P & K Midwest (Mt Vernon) | IA5758201 | NTNCWS | Oxford | 82 | Linn County |
| Palace Park Mhc | IA9433601 | CWS | Madrid | 426 | Webster County |
| Palmer Water Supply | IA7622024 | CWS | Palmer | 138 | Pocahontas County |
| Palo Water Supply | IA5765101 | CWS | Palo | 1,407 | Linn County |
| Panama Water Works | IA8355025 | CWS | Panama | 235 | Shelby County |
| Panora Water Works | IA3971026 | CWS | Panora | 1,142 | Guthrie County |
| Park Plaza Mhp Llc | IA7048601 | CWS | Oxford | 188 | Muscatine County |
| Park View Village | IA7736301 | CWS | Ankeny | 1,800 | Polk County |
| Park View Water & Sanitary District | IA8200855 | CWS | Eldridge | 2,389 | Scott County |
| Parkersburg Water Supply | IA1281028 | CWS | Parkersburg | 2,019 | Butler County |
| Parkview Mobile Home Court | IA5200603 | CWS | Oxford | 300 | Johnson County |
| Pathway Christian School | IA9233501 | NTNCWS | Kalona | 115 | Johnson County, Washington County |
| Paullina Municipal Water Supply | IA7139032 | CWS | Paullina | 996 | O'Brien County |
| Penn Center Inc | IA2800901 | CWS | Delhi | 89 | Delaware County |
| Peosta Water Supply | IA3170001 | CWS | Peosta | 2,278 | Dubuque County |
| Peterson Municipal Water Supply | IA2154039 | CWS | Peterson | 322 | Clay County |
| Pierson Water Supply | IA9766041 | CWS | Pierson | 345 | Woodbury County |
| Pilot Mound Water System | IA0862042 | CWS | Pilot Mound | 176 | Boone County |
| Pine Grove Mennonite School | IA4509501 | NTNCWS | Chester | 48 | Howard County |
| Pinecrest Mhp | IA4236601 | CWS | Eldora | 113 | Hardin County |
| Pineo Grove Water Company | IA8273062 | CWS | Le Claire | 58 | Scott County |
| Pints Water Association | IA1037301 | CWS | Independence | 96 | Buchanan County |
| Pioneer Hi Bred Marion Research | IA5751102 | NTNCWS | Oxford | 44 | Linn County |
| Pioneer Hi-Bred Durant Plant | IA1636101 | NTNCWS | Durant | 134 | Cedar County |
| Pisgah Water Supply | IA4364044 | CWS | Pisgah | 245 | Harrison County |
| Plainfield Water Supply | IA0960045 | CWS | Plainfield | 393 | Bremer County |
| Plantation Country View Subdivision | IA9680301 | CWS | Fredericksburg | 32 | Winneshiek County |
| Pleasant Valley Le Llc | IA7767601 | CWS | Newton | 350 | Polk County |
| Pleasantville Water Works | IA6377046 | CWS | Pleasantville | 1,676 | Marion County |
| Plover Water Supply | IA7628047 | CWS | Algona | 50 | Pocahontas County |
| Plymouth Water Supply | IA1759048 | CWS | Plymouth | 378 | Cerro Gordo County |
| Pocahontas Water Department | IA7633049 | CWS | Pocahontas | 1,877 | Pocahontas County |
| Poet Biorefining (Coon Rapids) | IA3907801 | NTNCWS | Coon Rapids | 57 | Guthrie County |
| Poet Biorefining - Fairbank Llc | IA1025202 | NTNCWS | Fairbank | 62 | Buchanan County |
| Poet Biorefining-Hanlontown, Llc | IA9830202 | NTNCWS | Hanlontown | 45 | Worth County |
| Poet Biorefining-Shell Rock Llc | IA1286801 | NTNCWS | Fredericksburg | 70 | Butler County |
| Polk Avenue Water Association | IA5200899 | CWS | Solon | 28 | Johnson County |
| Pomeroy Water Supply | IA1363051 | CWS | Pomeroy | 671 | Calhoun County |
| Ponderosa Park Mhp | IA8222612 | CWS | Davenport | 320 | Scott County |
| Ponderosa Utilities Inc. | IA7950300 | CWS | Montezuma | 1,750 | Poweshiek County |
| Pony Creek #1 Hoa | IA6500823 | CWS | Pacific Junction | 125 | Mills County |
| Postville Water Department | IA0375053 | CWS | Postville | 2,513 | Allamakee County, Clayton County |
| Poweshiek Water Association (Cr) | IA5715702 | CWS | Tama | 2,000 | Benton County |
| Poweshiek Water Association (Iac) | IA4868701 | CWS | Tama | 2,490 | Iowa County |
| Prairie City Water Works | IA5064055 | CWS | Prairie City | 1,703 | Jasper County |
| Prairie Farms Dairy, Inc. | IA2254102 | NTNCWS | Luana | 205 | Clayton County |
| Prairie View Estates Assoc Johnson Cnty | IA5225326 | CWS | Iowa City | 155 | Johnson County |
| Prairieburg Muni. Water Supply | IA5772054 | CWS | Prairieburg | 160 | Linn County |
| Precision Pulley And Idler-Humboldt | IA4641128 | NTNCWS | Pella | 100 | Humboldt County |
| Prestage Foods Of Iowa | IA9926102 | NTNCWS | Eagle Grove | 800 | Wright County |
| Preston Muni Water Supply | IA4965057 | CWS | Preston | 949 | Jackson County |
| Primghar Municipal Water Supply | IA7155059 | CWS | Primghar | 902 | O'Brien County |
| Princeton Water Supply | IA8273061 | CWS | Princeton | 923 | Scott County |
| Protivin Water Supply | IA4552063 | CWS | Protivin | 269 | Howard County |
| Pulaski Municipal Water Dept | IA2662064 | CWS | Milton | 264 | Davis County |
| Quality Water, Inc. #2 (K-L) | IA3126303 | CWS | Dubuque | 70 | Dubuque County |
| Quimby Water Supply | IA1855066 | CWS | Quimby | 249 | Cherokee County |
| Radcliffe Municipal Water | IA4283067 | CWS | Radcliffe | 561 | Hardin County |
| Rail One Usa | IA2326108 | NTNCWS | Le Claire | 30 | Clinton County |
| Rake Water Supply | IA9575068 | CWS | Whittemore | 186 | Winnebago County |
| Ralston Water Treatment Plant | IA1471069 | CWS | Glidden | 75 | Carroll County |
| Rancho Valley Homeowners Assoc | IA7038800 | CWS | Muscatine | 97 | Muscatine County |
| Randall Water Supply | IA4039071 | CWS | Randall | 154 | Hamilton County |
| Randolph Water Works | IA3649072 | CWS | Marshalltown | 192 | Fremont County |
| Rapid Creek Ridge | IA5225387 | CWS | Oxford | 70 | Johnson County |
| Rathbun Regional Water (Mount Pleasant) | IA4453901 | CWS | Centerville | 1,465 | Henry County |
| Readlyn Water Supply | IA0965073 | CWS | Readlyn | 845 | Bremer County |
| Redfield Water Works | IA2564074 | CWS | Redfield | 746 | Dallas County |
| Redwing Estates Hoa | IA5225313 | CWS | Oxford | 48 | Johnson County |
| Regency West Subdivision | IA3126308 | CWS | Dubuque | 34 | Dubuque County |
| Reinbeck Water Supply | IA3870073 | CWS | Gladbrook | 1,662 | Grundy County |
| Rembrandt Enterprises Inc (Rembrandt) | IA1170101 | NTNCWS | Laurens | 120 | Buena Vista County |
| Rembrandt Water Supply | IA1170078 | CWS | Newell | 209 | Buena Vista County |
| Remsen Municipal Utilities | IA7568079 | CWS | Remsen | 1,678 | Plymouth County |
| Renwick Munic Water Supply | IA4669080 | CWS | Renwick | 234 | Humboldt County |
| Responsible Transportation Llc | IA5475101 | NTNCWS | Sigourney | 60 | Keokuk County |
| Revelle 1St & 2Nd Subdivision | IA8215396 | CWS | Blue Grass | 54 | Scott County |
| Revelle 6Th & 7Th Addition | IA8215301 | CWS | Blue Grass | 125 | Scott County |
| Rhodes Water Supply | IA6480081 | CWS | Rhodes | 271 | Marshall County |
| Riceville Water Supply | IA4558001 | CWS | Riceville | 816 | Howard County, Mitchell County |
| Richland Water Supply | IA5470083 | CWS | Brighton | 542 | Keokuk County |
| Ridgeway, City Of | IA9680085 | CWS | Ridgeway | 275 | Winneshiek County |
| Rinard Water Supply | IA1374086 | CWS | Fort Dodge | 38 | Calhoun County |
| Ringsted Water Supply | IA3275087 | CWS | Ringsted | 365 | Emmet County |
| Ripleys Mhc Ia Llc | IA7000600 | CWS | Leclaire | 520 | Muscatine County |
| River Heights Property Owners Assoc. | IA5200318 | CWS | Oxford | 390 | Johnson County |
| River Highlands Subdivision | IA8245303 | CWS | Davenport | 63 | Scott County |
| River Oaks Development | IA2570302 | CWS | Ankeny | 215 | Dallas County |
| River Ridge Hoa | IA1037302 | CWS | Independence | 60 | Buchanan County |
| River Valley Cooperative | IA1684101 | NTNCWS | Wilton | 30 | Cedar County |
| Riverside Water Supply | IA9260090 | CWS | Riverside | 1,060 | Washington County |
| Riverton Water Works | IA3655071 | CWS | Riverton | 250 | Fremont County |
| Riverview Estates | IA5200347 | CWS | Iowa City | 108 | Johnson County |
| Rj Thomas Manufacturing Co Inc | IA1811102 | NTNCWS | Cherokee | 75 | Cherokee County |
| Rock Rapids Municipal Water Works | IA6065092 | CWS | Rock Rapids | 2,611 | Lyon County |
| Rock Valley Rural Water District | IA8482701 | CWS | Rock Valley | 2,250 | Sioux County |
| Rockford Water Supply | IA3430091 | CWS | Rockford | 762 | Floyd County |
| Rocklyn Mhp | IA7780601 | CWS | Homestead | 103 | Polk County |
| Rockwell City Water Supply | IA1376098 | CWS | Rockwell City | 2,250 | Calhoun County |
| Rockwell Water Supply | IA1773097 | CWS | Rockwell | 1,071 | Cerro Gordo County |
| Rocky Knoll Mhp | IA9525601 | CWS | Leland | 49 | Winnebago County |
| Rodman Water System | IA7428022 | CWS | West Bend | 31 | Palo Alto County |
| Roland Water Supply | IA8570001 | CWS | Roland | 1,394 | Story County |
| Rolfe Water Supply | IA7639002 | CWS | Rolfe | 509 | Pocahontas County |
| Rolling Acres Subdivision | IA7048310 | CWS | Muscatine | 115 | Muscatine County |
| Rome Water Supply | IA4475001 | CWS | Washington | 114 | Henry County |
| Rowan Muni Water Supply | IA9958004 | CWS | Manly | 124 | Wright County |
| Royal Oaks Subdivision | IA5282303 | CWS | Oxford | 163 | Johnson County |
| Rudd Waterworks | IA3440007 | CWS | Rudd | 358 | Floyd County |
| Russell Water Supply | IA5939009 | CWS | Russell | 477 | Lucas County |
| Rustic Oaks Homeowners Assn. | IA8215399 | CWS | Muscatine | 100 | Scott County |
| Ruthven Water Supply | IA7465010 | CWS | Ruthven | 779 | Palo Alto County |
| Rutland Water Supply | IA4675012 | CWS | Gilmore City | 116 | Humboldt County |
| Ruveon Llc | IA7048161 | NTNCWS | Muscatine | 575 | Muscatine County |
| Ryan Water Supply | IA2864013 | CWS | Ryan | 350 | Delaware County |
| Sabula Water Supply | IA4975014 | CWS | Sabula | 506 | Jackson County |
| Sac City Municipal Water Plant | IA8150015 | CWS | Sac City | 2,093 | Sac County |
| Sageville Elementary School | IA3126590 | NTNCWS | Dubuque | 310 | Dubuque County |
| Saint Marys Water Corporation | IA9176019 | CWS | Saint Charles | 121 | Warren County |
| Saint Olaf Water Supply | IA2277020 | CWS | Monona | 106 | Clayton County |
| Saints Avenue Apartments | IA0990990 | CWS | Waverly | 125 | Bremer County |
| Salem Water Supply | IA4478023 | CWS | Salem | 396 | Henry County |
| Salix Water Supply | IA9770024 | CWS | Salix | 295 | Woodbury County |
| Sanborn Water Supply | IA7165025 | CWS | Sanborn | 1,392 | O'Brien County |
| Sapp Bros Travel Centers | IA3643202 | NTNCWS | Glenwood | 1,074 | Fremont County |
| Scarville Lutheran Church | IA9580801 | NTNCWS | Lake Mills | 95 | Winnebago County |
| Scattergood Friends School | IA1694562 | NTNCWS | West Branch | 100 | Cedar County |
| Scenic Acres | IA2200901 | CWS | St. Olaf | 27 | Clayton County |
| Scenic View Estates | IA9630307 | CWS | Fredericksburg | 78 | Winneshiek County |
| Schaller Water Supply | IA8156028 | CWS | Schaller | 729 | Sac County |
| Schleswig Munic Water Supply | IA2446029 | CWS | Schleswig | 803 | Crawford County |
| Scranton Water System | IA3759031 | CWS | Scranton | 511 | Greene County |
| Seed Savers Exchange | IA9630206 | NTNCWS | Decorah | 100 | Winneshiek County |
| Seymour Municipal Utility Water Dept | IA9368035 | CWS | Seymour | 637 | Wayne County |
| Shagbark Estates | IA3126345 | CWS | Dubuque | 38 | Dubuque County |
| Shambaugh Muni Water Supply | IA7380036 | CWS | Shambaugh | 159 | Page County |
| Sharon Bethel Church/School | IA5221501 | NTNCWS | Kalona | 195 | Johnson County |
| Sheffield Water Supply | IA3570037 | CWS | Sheffield | 1,130 | Franklin County |
| Shelby Water Supply | IA8369038 | CWS | Shelby | 727 | Shelby County |
| Sheldahl Water Supply | IA7778039 | CWS | Sheldahl | 307 | Polk County |
| Shell Rock Muni Water Supp | IA1286042 | CWS | Shell Rock | 1,269 | Butler County |
| Shellsburg Water Supply | IA0670043 | CWS | Shellsburg | 961 | Benton County |
| Sherman Place Water & Road, Inc. | IA9630303 | CWS | Fredericksburg | 73 | Winneshiek County |
| Shueyville United Methodist Church | IA5280801 | NTNCWS | Oxford | 410 | Johnson County |
| Sibley Public Water Supply | IA7245047 | CWS | Sibley | 2,860 | Osceola County |
| Sidney Water Supply | IA3661048 | CWS | Sidney | 1,077 | Fremont County |
| Sigourney Muni Water Works | IA5475050 | CWS | Sigourney | 2,004 | Keokuk County |
| Silver City Water Supply | IA6575052 | CWS | Marshalltown | 245 | Mills County |
| Sioux Rapids Water Department | IA1175056 | CWS | Sioux Rapids | 932 | Buena Vista County, Clay County |
| Sirwa #1 (Greenfield) | IA0140701 | CWS | Creston | 1,712 | Adair County |
| Sirwa #3 (Leon) | IA2718755 | CWS | Creston | 1,373 | Decatur County |
| Sirwa - Corning | IA0207704 | CWS | Creston | 2,585 | Adams County, Union County |
| Slater Muni Water Dept | IA8580057 | CWS | Slater | 1,548 | Story County |
| Sloan Water Supply | IA9780059 | CWS | Sloan | 1,042 | Woodbury County |
| Smithland Water Supply | IA9783060 | CWS | Smithland | 181 | Monona County, Woodbury County |
| Soldier Water Supply | IA6749061 | CWS | Soldier | 180 | Monona County |
| Solon Water Dept | IA5282062 | CWS | Solon | 3,018 | Johnson County |
| Somers Water Works | IA1381073 | CWS | Somers | 128 | Calhoun County |
| South Amana Water Supply | IA4868034 | CWS | Amana | 300 | Iowa County |
| South English Water Supply | IA5478074 | CWS | South English | 238 | Keokuk County |
| Southdale Home Owners Assn | IA5500822 | CWS | Whittemore | 70 | Kossuth County |
| Southland Mhp Community | IA7727610 | CWS | Boca Raton | 195 | Polk County |
| Southridge Estate | IA7727603 | CWS | Newton | 648 | Polk County, Warren County |
| Southshore Heights | IA6342308 | CWS | Newton | 138 | Marion County |
| Southwest Polk Water Service, Inc. | IA7700802 | CWS | Ankeny | 393 | Polk County |
| Southwest Reg Water District (Clarinda) | IA7383901 | CWS | Clarinda | 2,942 | Page County |
| Southwest Reg Water District (Red Oak) | IA6950701 | CWS | Clarinda | 3,500 | Montgomery County |
| Spillville Water Supply | IA9686077 | CWS | Spillville | 371 | Winneshiek County |
| Spring Valley Homeowners Assn. | IA5225303 | CWS | Iowa City | 163 | Johnson County |
| Spring Valley Park | IA3100606 | CWS | Dubuque | 180 | Dubuque County |
| Springbrook Water Dept | IA4984086 | CWS | Springbrook | 144 | Jackson County |
| Springville Water Supply | IA5782087 | CWS | Springville | 1,164 | Linn County |
| Squaw Valley South Subdivision | IA8503305 | CWS | State Center | 105 | Story County |
| Ssab Iowa Inc | IA7038101 | NTNCWS | Muscatine | 760 | Muscatine County |
| St Ansgar Water Supply | IA6673016 | CWS | St. Ansgar | 1,161 | Mitchell County |
| St Johns Lutheran Church | IA5343815 | NTNCWS | Monticello | 157 | Jones County |
| Stacyville Water Supply | IA6677089 | CWS | Stacyville | 465 | Mitchell County |
| Stanhope Water Department | IA4045090 | CWS | Stanhope | 364 | Hamilton County |
| Stanwood Water Supply | IA1681092 | CWS | Stanwood | 637 | Cedar County |
| Star Water | IA3126316 | CWS | Dubuque | 110 | Dubuque County |
| Starmont Community School District | IA3307571 | NTNCWS | Arlington | 742 | Clayton County, Fayette County |
| State Center Muni Water Dept | IA6484093 | CWS | State Center | 1,411 | Marshall County |
| Steamboat Association | IA7048303 | CWS | Muscatine | 29 | Muscatine County |
| Steamboat Rock Water Dept | IA4289094 | CWS | Steamboat Rock | 264 | Hardin County |
| Stockport Water Supply | IA8973095 | CWS | Stockport | 272 | Van Buren County |
| Stockton Muni Water Supply | IA7063096 | CWS | Calamus | 176 | Muscatine County |
| Stoney Creek North | IA8271302 | CWS | Blue Grass | 50 | Scott County |
| Stoney Creek Subdivision | IA8271301 | CWS | Davenport | 70 | Scott County |
| Stoney Pointe Subdivision | IA5225317 | CWS | Washington | 27 | Johnson County |
| Stout Water Supply | IA3880001 | CWS | Stout | 191 | Grundy County |
| Stover Heights Mhc | IA7727605 | CWS | Madrid | 393 | Polk County |
| Stratford Muni Water Dept | IA4051002 | CWS | Stratford | 707 | Hamilton County |
| Strawberry Point Water Supply | IA2279003 | CWS | Strawberry Point | 1,155 | Clayton County |
| Stuart Water Supply | IA0180001 | CWS | Stuart | 1,814 | Adair County, Guthrie County |
| Sully Muni Water Works | IA5076005 | CWS | Sully | 900 | Jasper County |
| Sumner Water Supply | IA0970006 | CWS | Sumner | 2,030 | Bremer County, Fayette County |
| Sunfield Mobile Home Community | IA9133603 | CWS | Indianola | 80 | Warren County |
| Sunnybrook Mobile Home Park | IA7700601 | CWS | Newton | 343 | Polk County |
| Sunnyside Village Mhp Llc | IA4300600 | CWS | Missouri Valley | 190 | Harrison County |
| Sunrise Mhc | IA0819602 | CWS | Madrid | 95 | Boone County |
| Sunrise Mill | IA6368601 | CWS | Pella | 237 | Marion County |
| Sunrise Terrace Mhc | IA5059601 | CWS | Newton | 330 | Jasper County, Marshall County |
| Sunrise Village Mobile Home Pk | IA5200602 | CWS | Grinnell | 340 | Johnson County |
| Sunset Hills Estates Part 2 | IA9233301 | CWS | Kalona | 45 | Washington County |
| Sunset Village | IA6469601 | CWS | Newton | 528 | Marshall County |
| Super 20 Mobile Home Court | IA3126603 | CWS | Boca Raton | 236 | Dubuque County |
| Superior Water System | IA3073001 | CWS | Superior | 135 | Dickinson County |
| Sutherland Water Supply | IA7177007 | CWS | Sutherland | 629 | O'Brien County |
| Swaledale Water Supply | IA1778008 | CWS | Marshalltown | 144 | Cerro Gordo County |
| Swea City Water Supply | IA5584009 | CWS | Swea City | 584 | Kossuth County |
| Switch | IA6527545 | NTNCWS | Glenwood Ia | 285 | Mills County |
| Syngenta Seeds Llc | IA5240101 | NTNCWS | Lone Tree | 75 | Johnson County |
| Table Mound Park | IA3100600 | CWS | Cascasde | 455 | Dubuque County |
| Tabor Water Supply | IA3667012 | CWS | Tabor | 1,014 | Fremont County, Mills County |
| Tama Water Supply | IA8670013 | CWS | Tama | 3,130 | Tama County |
| Tasc Inc. | IA0398801 | NTNCWS | Waukon | 70 | Allamakee County |
| Templeton Water Supply | IA1479015 | CWS | Templeton | 352 | Carroll County |
| Terrace Acres Subdivision | IA5291303 | CWS | Kalona | 25 | Johnson County |
| Terrace Heights | IA3126604 | CWS | Denver | 548 | Dubuque County |
| Terrace Manor Mobile Home Park | IA6457601 | CWS | Legrand | 93 | Marshall County |
| Terril Municipal Waterworks | IA3080016 | CWS | Terril | 334 | Dickinson County |
| Terry Water Association | IA0690304 | CWS | Fairfax | 25 | Benton County |
| The Learning Journey | IA7820502 | NTNCWS | Council Bluffs | 90 | Pottawattamie County |
| The Meadows | IA5225321 | CWS | Coralville | 35 | Johnson County |
| The Meadows | IA7727609 | CWS | Phoenix | 702 | Polk County |
| Thompson Water Works | IA9585017 | CWS | Thompson | 499 | Winnebago County |
| Thor Water Works | IA4680018 | CWS | Vincent | 181 | Humboldt County |
| Thornton Water Supply | IA1781019 | CWS | Belmond | 400 | Cerro Gordo County |
| Thunder Hills Home & Utility Assoc. | IA3170335 | CWS | Epworth | 300 | Dubuque County |
| Thurman Water Works | IA3671021 | CWS | Tabor | 167 | Fremont County |
| Tiffin Water Supply | IA5288021 | CWS | Tiffin | 7,577 | Johnson County |
| Timber Lake Estates Hoa | IA8215306 | CWS | Blue Grass | 83 | Scott County |
| Timber Ridge | IA0600600 | CWS | Dewitt | 225 | Benton County |
| Timber Trails Homeowners Association | IA5200303 | CWS | Iowa City | 80 | Johnson County |
| Timber Valley Estates (1St & 2Nd Add) | IA8215384 | CWS | Blue Grass | 132 | Scott County |
| Timber Valley Estates (Third Addition) | IA8215385 | CWS | Blue Grass | 73 | Scott County |
| Timberlake | IA5200810 | CWS | Oxford | 52 | Johnson County |
| Timberlane Water Association | IA9433336 | CWS | Fort Dodge | 48 | Webster County |
| Timberline Estates | IA9260302 | CWS | Crawfordsville | 95 | Washington County |
| Timberline Estates, Ltd. | IA2900626 | CWS | West Burlington | 712 | Des Moines County |
| Tipton Water Supply | IA1689022 | CWS | Tipton | 3,149 | Cedar County |
| Titonka Water Supply | IA5588026 | CWS | Titonka | 511 | Kossuth County |
| Toledo Water Supply | IA8676027 | CWS | Toledo | 2,399 | Tama County |
| Traer Municipal Water Plant | IA8681030 | CWS | Traer | 1,583 | Tama County |
| Treynor Water Department | IA7866031 | CWS | Underwood | 1,049 | Pottawattamie County |
| Tripoli Water Supply | IA0975032 | CWS | Tripoli | 1,191 | Bremer County |
| Trout Valley 2Nd Addition | IA8209301 | CWS | Leclaire | 85 | Scott County |
| Trout Valley Homes Assoc. 1 | IA8209398 | CWS | Leclaire | 72 | Scott County |
| Truckomat Corporation | IA8285200 | NTNCWS | Walcott | 1,794 | Scott County |
| Truesdale Water Supply | IA1182035 | CWS | Spencer | 69 | Buena Vista County |
| Truro Waterworks | IA6167036 | CWS | Truro | 525 | Madison County |
| Turkey Creek Development | IA5225316 | CWS | Iowa City | 65 | Johnson County |
| Turkey Valley Community School | IA9661531 | NTNCWS | Jackson Junction | 490 | Winneshiek County |
| Twin Knolls Fourth/Fifth Addition | IA5784326 | CWS | Cedar Rapids | 90 | Linn County |
| Twin Lakes Utilities | IA1300101 | CWS | Rockwell City | 300 | Calhoun County |
| Twin Valley Lakes Improvement Assn | IA5200861 | CWS | Solon | 100 | Johnson County |
| Twin View Heights | IA5282301 | CWS | Solon | 155 | Johnson County |
| Tyson Fresh Meats Inc (Columbus Jct) | IA5815101 | NTNCWS | Columbus Junction | 1,300 | Louisa County |
| Union Water Supply | IA4291038 | CWS | Newton | 399 | Hardin County |
| Urbana Water Supply | IA0680041 | CWS | Urbana | 1,562 | Benton County |
| Us Foods | IA5208104 | NTNCWS | Coralville | 50 | Johnson County |
| Us Nameplate Company Inc | IA5758101 | NTNCWS | Mount Vernon | 65 | Linn County |
| Ute Water Supply | IA6762043 | CWS | Ute | 338 | Monona County |
| Vail Water Supply | IA2452044 | CWS | Vail | 383 | Crawford County |
| Val Vista Estates | IA7727607 | CWS | Des Moines | 553 | Polk County |
| Valero Lakota Plant | IA5540101 | NTNCWS | Lakota | 65 | Kossuth County |
| Valley Heights 1St Annex | IA8215305 | CWS | Blue Grass | 70 | Scott County |
| Valley View Estates #1 And #2 | IA7048332 | CWS | Muscatine | 89 | Muscatine County |
| Valley View Water Association | IA4300601 | CWS | Missouri Valley | 65 | Harrison County |
| Van Horne Water Works | IA0685045 | CWS | Van Horne | 779 | Benton County |
| Van Meter Municipal Water Work | IA2570046 | CWS | Van Meter | 1,074 | Dallas County |
| Vander Haag'S Inc | IA6525103 | NTNCWS | Spencer | 47 | Mills County |
| Varina Water Supply | IA7642047 | CWS | Varina | 68 | Pocahontas County |
| Vca Avondale Animal Hospital | IA7727201 | NTNCWS | Des Moines | 64 | Polk County |
| Ventura Water Works | IA1785032 | CWS | Ventura | 717 | Cerro Gordo County |
| Vermeer (Griswold) | IA1545101 | NTNCWS | Griswold | 52 | Cass County |
| Vern Acres (Oliphant Addition) | IA5784303 | CWS | Cedar Rapids | 150 | Linn County |
| Victor Municipal Water Dept | IA4875050 | CWS | Belle Plaine | 875 | Iowa County, Poweshiek County |
| Village Oaks Homeowners Assn | IA8215304 | CWS | Muscatine | 250 | Muscatine County, Scott County |
| Villisca Municipal Water Dept | IA6985051 | CWS | Villisca | 1,132 | Montgomery County |
| Vincent Water Supply | IA9486052 | CWS | Vincent | 130 | Webster County |
| Vista Hills Water Association | IA8209359 | CWS | Leclaire | 45 | Scott County |
| Vista Village Mhc | IA6377601 | CWS | Knoxville | 110 | Marion County |
| Volga Water Supply | IA2285055 | CWS | Volga | 203 | Clayton County |
| W Central Rwa - Denison Subsys | IA2424701 | CWS | Manning | 2,428 | Crawford County |
| Wabash Greenhouse | IA7820207 | NTNCWS | Council Bluffs | 42 | Pottawattamie County |
| Wadena Water System | IA3371056 | CWS | Wadena | 209 | Fayette County |
| Wahpeton Water Supply | IA3087057 | CWS | Milford | 408 | Dickinson County |
| Walcott Waterworks | IA8285058 | CWS | Walcott | 1,551 | Scott County |
| Waldenburg Community Water System | IA4802301 | CWS | Oxford | 90 | Iowa County |
| Waldschmidt Subdivision | IA9260301 | CWS | Iowa City | 45 | Washington County |
| Walker Water Works | IA5792059 | CWS | Walker | 688 | Linn County |
| Wall Lake Water Supply | IA8166061 | CWS | Wall Lake | 780 | Sac County |
| Wallingford Municipal Waterworks | IA3290060 | CWS | Wallingford | 170 | Emmet County |
| Walnut Municipal Utilities | IA7872062 | CWS | Walnut | 768 | Pottawattamie County |
| Walnut Street Well | IA0690305 | CWS | Walford | 45 | Benton County |
| Walters Mobile Home Park | IA2258601 | CWS | Waukon | 25 | Clayton County |
| Wapello Municipal Water Works | IA5879063 | CWS | Wapello | 1,977 | Louisa County |
| Wapsie Valley Creamery, Inc. | IA1037103 | NTNCWS | Independence | 60 | Buchanan County |
| Washta Water Supply | IA1880073 | CWS | Washta | 209 | Cherokee County |
| Waucoma Water Supply | IA3375001 | CWS | Spillville | 229 | Fayette County |
| Wayland Water Supply | IA4490091 | CWS | Wayland | 966 | Henry County |
| Webster Municipal Water Works | IA5491093 | CWS | South English | 96 | Keokuk County |
| Wellman Municipal Waterworks | IA9276096 | CWS | Muscatine | 1,524 | Washington County |
| Wells Ag Supply | IA7603101 | NTNCWS | Fonda | 44 | Pocahontas County |
| Wellsburg Water Supply | IA3890097 | CWS | Wellsburg | 721 | Grundy County |
| Welton Water Supply | IA2391001 | CWS | Calamus | 121 | Clinton County |
| Wendram Bluff Homes Water System | IA5225306 | CWS | Iowa City | 68 | Johnson County |
| Wesley Water Supply | IA5592098 | CWS | Wesley | 390 | Kossuth County |
| West Bend Water Department | IA7470099 | CWS | West Bend | 772 | Kossuth County, Palo Alto County |
| West Branch Mhp | IA1600682 | CWS | Oxford | 400 | Cedar County |
| West Branch Water Works | IA1694000 | CWS | West Branch | 2,509 | Cedar County |
| West Chester Muni Wtr Supply | IA9281006 | CWS | Muscatine | 144 | Washington County |
| West Liberty Foods | IA7073834 | NTNCWS | West Liberty | 925 | Muscatine County |
| West Okoboji | IA3090081 | CWS | Milford | 308 | Dickinson County |
| West Point Muni Water System | IA5691012 | CWS | West Point | 921 | Lee County |
| West Post Estates Addition | IA5731301 | CWS | Cedar Rapids | 85 | Linn County |
| West Union Water Supply | IA3383014 | CWS | West Union | 2,540 | Fayette County |
| Westcott Heights Hoa Part Three | IA5225327 | CWS | Tipton | 120 | Johnson County |
| Westcott Heights Parts 1 & 2 | IA5225325 | CWS | Tipton | 63 | Johnson County |
| Western Hills (Mobile) Estates | IA5208600 | CWS | Grinnell | 760 | Johnson County |
| Westfield Water Supply | IA7589008 | CWS | Newell | 123 | Plymouth County |
| Westgate Water Supply | IA3379009 | CWS | Westgate | 192 | Fayette County |
| Westside Water Supply | IA2458023 | CWS | Westside | 277 | Crawford County |
| Westwood Water Supply | IA4453318 | CWS | Crawfordsville | 101 | Henry County |
| What Cheer Water Supply | IA5493016 | CWS | Sigourney | 646 | Keokuk County |
| Wheatland City Water Supply | IA2394017 | CWS | Wheatland | 775 | Clinton County |
| Wheel Estates Mhc | IA6342301 | CWS | Knoxville | 315 | Marion County, Monroe County |
| Whiting Water Supply | IA6769018 | CWS | Whiting | 727 | Monona County |
| Whittemore Muni Water Supply | IA5595020 | CWS | Whittemore | 522 | Kossuth County |
| Wildlife Estates | IA7063301 | CWS | Blue Grass | 70 | Muscatine County |
| Wildwood Water Corporation | IA2570301 | CWS | Ankeny | 170 | Dallas County |
| Williams Water Supply | IA4070022 | CWS | Williams | 315 | Hamilton County |
| Williamsburg Public Water Supply | IA4884023 | CWS | Williamsburg | 3,345 | Iowa County |
| Willow Stream Estates Mobile Home | IA8230301 | CWS | Leclaire | 110 | Scott County |
| Wilshire Hills Mhc | IA9164601 | CWS | Madrid | 216 | Warren County |
| Wilton Water Supply | IA7078026 | CWS | Wilton | 2,924 | Muscatine County |
| Winchester Heights Subdivision | IA5285302 | CWS | Swisher | 67 | Johnson County |
| Winding Brook Mobile Home Park | IA2300607 | CWS | Lowden | 150 | Clinton County |
| Windy Ridge Well Association | IA5748300 | CWS | Oxford | 45 | Linn County |
| Winfield Muni Water Dept | IA4493028 | CWS | Winfield | 1,035 | Henry County |
| Winnavegas Casino | 070000014 | NTNCWS | Sloan | 1,576 | |
| Winthrop Water Supply | IA1093031 | CWS | Winthrop | 840 | Buchanan County |
| Wiota Water Works | IA1570032 | CWS | Wiota | 95 | Cass County |
| Woden Water Supply | IA4170033 | CWS | Woden | 188 | Hancock County |
| Woodbine Water Department | IA4388034 | CWS | Woodbine | 1,625 | Harrison County |
| Woodland Acres | IA9433600 | CWS | Fort Dodge | 110 | Webster County |
| Woodland Heights Homeowners Assoc. | IA5225309 | CWS | Tipton | 41 | Johnson County |
| Woodland Ridge Estates | IA5225333 | CWS | Oxford | 42 | Johnson County |
| Woodland Wapello Mobile Home Park | IA5879601 | CWS | Muscatine | 126 | Louisa County |
| Woodlyn Hills | IA5502319 | CWS | Whittemore | 80 | Kossuth County |
| Woods And Meadows Subdivision | IA8245357 | CWS | Leclaire | 148 | Scott County |
| Woods At Hunter Creek (Part 1) | IA5280304 | CWS | Iowa City | 50 | Johnson County |
| Woodward Resource Center | IA0800923 | CWS | Woodward | 700 | Boone County |
| Woodward Water Supply | IA2576036 | CWS | Woodward | 1,346 | Dallas County |
| Woolstock Water Supply | IA9970037 | CWS | Woolstock | 144 | Wright County |
| Worthington Water Supply | IA3189001 | CWS | Worthington | 382 | Dubuque County |
| Wright County Agribusiness Park | IA9926103 | NTNCWS | Gilmore City | 25 | Wright County |
| Wyoming Water System | IA5396039 | CWS | Wyoming | 523 | Jones County |
| Xenia Rwd (Madrid) | IA0848701 | CWS | Bouton | 1,635 | Boone County, Dallas County, Polk County |
| Yale Water Supply | IA3980040 | CWS | Yale | 267 | Guthrie County |
| Yankee Grove Hoa | IA5784321 | CWS | Oxford | 64 | Cedar County |
| Yankee Grove Part 3 | IA1667301 | CWS | Coralville | 25 | Cedar County |
| Yes Five Seasons Cedar Llc | IA5715602 | CWS | Newton | 994 | Linn County |
| Yes Regency Manor Llc | IA7727602 | CWS | Newton | 710 | Polk County |
| Yes Western Village Llc | IA7785601 | CWS | Newton | 670 | Polk County |
| Yetter Municipal Water Supply | IA1393001 | NTNCWS | Auburn | 25 | Calhoun County |
| Zearing Water Department | IA8590041 | CWS | Zearing | 528 | Story County |