| 1 | CHARITON MUNICIPAL WATER WORKS Chariton | Chariton | Surface Water | 82 | 4,381 | Yes |
| 2 | GRINNELL WATER DEPARTMENT Grinnell | Grinnell | Groundwater | 35 | 9,564 | Yes |
| 3 | LEON WATER SUPPLY Leon | Leon | Surface Water | 22 | 1,830 | Yes |
| 4 | DYERSVILLE MUNICIPAL WATER CO Dyersville | Dyersville | Groundwater | 16 | 4,477 | Yes |
| 5 | OSCEOLA WATER WORKS Osceola | Osceola | Surface Water | 13 | 5,503 | Yes |
| 6 | SAC & FOX (MESKWAKI) IN IOWA Tama | Tama | Groundwater | 12 | 4,765 | Yes |
| 7 | DONNELLSON MUNI WATER WORKS Donnellson | Donnellson | Groundwater | 12 | 885 | Yes |
| 8 | EARLY MUNICIPAL WATER SUPPLY Early | Early | Groundwater | 11 | 587 | Yes |
| 9 | SIOUX CITY WATER SUPPLY Sioux City | Sioux City | Surface Water | 10 | 85,791 | Yes |
| 10 | LAMONI MUNICIPAL UTILITIES Lamoni | Lamoni | Surface Water | 8 | 2,029 | Yes |
| 11 | BOONE WATER WORKS Boone | Boone | Surface Water | 7 | 12,704 | Yes |
| 12 | TOLEDO WATER SUPPLY Toledo | Toledo | Groundwater | 6 | 2,399 | Yes |
| 13 | BELLEVUE MUNICIPAL UTILITIES Bellevue | Bellevue | Groundwater | 5 | 2,363 | Yes |
| 14 | FAIRBANK WATER SUPPLY Fairbank | Fairbank | Groundwater | 5 | 1,111 | Yes |
| 15 | CORNING MUNI WATER DEPARTMENT Corning | Corning | Surface Water | 4 | 1,735 | Yes |
| 16 | WOODWARD WATER SUPPLY Woodward | Woodward | Groundwater | 4 | 1,346 | Yes |
| 17 | KEYSTONE WATER SUPPLY Keystone | Keystone | Groundwater | 4 | 599 | Yes |
| 18 | ALTOONA WATER SUPPLY Altoona | Altoona | Groundwater | 3 | 19,565 | Yes |
| 19 | SPIRIT LAKE WATERWORKS Spirit Lake | Spirit Lake | Surface Water | 3 | 6,167 | Yes |
| 20 | XENIA RWD (BOONE) Bouton | Bouton | Surface Water | 3 | 4,975 | Yes |
| 21 | REGIONAL WATER Avoca | Avoca | Surface Water | 3 | 4,132 | Yes |
| 22 | ROCK VALLEY RURAL WATER DISTRICT Rock Valley | Rock Valley | Groundwater | 3 | 2,230 | Yes |
| 23 | ATKINS MUNICIPAL WATER WORKS Atkins | Atkins | Groundwater | 3 | 2,056 | Yes |
| 24 | SLATER MUNI WATER DEPT Slater | Slater | Surface Water | 3 | 1,548 | Yes |
| 25 | PRINCETON WATER SUPPLY Princeton | Princeton | Groundwater | 3 | 923 | Yes |
| 26 | BLAIRSTOWN WATER SUPPLY Blairstown | Blairstown | Groundwater | 3 | 738 | Yes |
| 27 | ZEARING WATER DEPARTMENT Zearing | Zearing | Groundwater | 3 | 528 | Yes |
| 28 | DES MOINES WATER WORKS Des Moines | Des Moines | Surface Water | 2 | 246,055 | Yes |
| 29 | WATERLOO WATER WORKS Waterloo | Waterloo | Groundwater | 2 | 69,504 | Yes |
| 30 | UNIVERSITY WATER SYSTEM Iowa City | Iowa City | Surface Water | 2 | 26,684 | Yes |
| 31 | BURLINGTON MUNICIPAL WATERWORKS Burlington | Burlington | Surface Water | 2 | 26,015 | Yes |
| 32 | MAHASKA RURAL WATER SYSTEM, INC. Oskaloosa | Oskaloosa | Groundwater | 2 | 9,818 | Yes |
| 33 | CRESTON WATER SUPPLY Creston | Creston | Surface Water | 2 | 7,536 | Yes |
| 34 | WINTERSET MUNICIPAL WATERWORKS Winterset | Winterset | Surface Water | 2 | 5,428 | Yes |
| 35 | ANAMOSA MUNICIPAL WATER SUPPLY Anamosa | Anamosa | Groundwater | 2 | 4,457 | Yes |
| 36 | RURAL WATER SYSTEM #1 Hospers | Hospers | Surface Water | 2 | 3,428 | Yes |
| 37 | MADRID WATER DEPARTMENT Perry | Perry | Surface Water | 2 | 3,090 | Yes |
| 38 | MITCHELLVILLE WATER SUPPLY Mitchellville | Mitchellville | Groundwater | 2 | 2,515 | Yes |
| 39 | ROCKWELL CITY WATER SUPPLY Rockwell City | Rockwell City | Groundwater | 2 | 2,250 | Yes |
| 40 | GREENFIELD MUNICIPAL UTILITIES Greenfield | Greenfield | Surface Water | 2 | 2,227 | Yes |
| 41 | XENIA RWD (MADRID) Bouton | Bouton | Surface Water | 2 | 1,635 | Yes |
| 42 | LAKE VIEW WATER SUPPLY Lake View | Lake View | Groundwater | 2 | 1,133 | Yes |
| 43 | DANVILLE WATER SUPPLY Muscatine | Muscatine | Surface Water | 2 | 923 | Yes |
| 44 | NEWHALL WATER SUPPLY Van Horne | Van Horne | Groundwater | 2 | 881 | Yes |
| 45 | WALL LAKE WATER SUPPLY Wall Lake | Wall Lake | Groundwater | 2 | 780 | Yes |
| 46 | WHEATLAND CITY WATER SUPPLY Wheatland | Wheatland | Groundwater | 2 | 775 | Yes |
| 47 | EXIRA WATER DEPT Exira | Exira | Groundwater | 2 | 764 | Yes |
| 48 | SCHALLER WATER SUPPLY Schaller | Schaller | Groundwater | 2 | 729 | Yes |
| 49 | MARION MUNICIPAL WATER DEPT Marion | Marion | Groundwater | 1 | 41,623 | Yes |
| 50 | FARLEY WATER SUPPLY Farley | Farley | Groundwater | 1 | 1,766 | Yes |
| 51 | PLEASANTVILLE WATER WORKS Pleasantville | Pleasantville | Groundwater | 1 | 1,676 | Yes |
| 52 | CLARINDA TREATMENT COMPLEX Clarinda | Clarinda | Groundwater | 1 | 1,439 | Yes |
| 53 | AMANA SOCIETY WATER SYSTEM NORTH Amana | Amana | Groundwater | 1 | 1,248 | Yes |
| 54 | APLINGTON WATER SUPPLY Aplington | Aplington | Groundwater | 1 | 1,126 | Yes |
| 55 | MALVERN WATER SUPPLY Malvern | Malvern | Groundwater | 1 | 1,046 | Yes |
| 56 | LANSING WATER SUPPLY Lansing | Lansing | Groundwater | 1 | 983 | Yes |
| 57 | DE SOTO WATER SUPPLY Adel | Adel | Groundwater | 1 | 960 | Yes |
| 58 | ARMSTRONG WATER SUPPLY Armstrong | Armstrong | Groundwater | 1 | 918 | Yes |
| 59 | MONTROSE WATER WORKS Montrose | Montrose | Surface Water | 1 | 738 | Yes |
| 60 | WOODWARD RESOURCE CENTER Woodward | Woodward | Surface Water | 1 | 700 | Yes |
| 61 | POMEROY WATER SUPPLY Pomeroy | Pomeroy | Groundwater | 1 | 671 | Yes |
| 62 | DELMAR WATER SUPPLY Maquoketa | Maquoketa | Groundwater | 1 | 542 | Yes |