How many public water systems are in Iowa?

Iowa has 1,828 active public water systems in EPA SDWIS records, including 1,084 community water systems. Together they report serving 3.1M people.

What is the largest water system in Iowa?

Des Moines Water Works is the largest active public water system in Iowa, serving a reported 246,055 people.

Does Iowa rely more on groundwater or surface water?

92.2% of Iowa's active public water systems draw primarily on groundwater and 7.8% on surface water (including purchased supplies).

Iowa public water systems

1,828 active systems regulated under the Safe Drinking Water Act, serving a reported 3.1M people across 114 counties.

Dataset updated October 2026 . Source: EPA SDWIS/ECHO, refreshed quarterly.

Active systems

1,828

Population served

3.1M

Community systems

1,084

Groundwater share

92.2%

System types in Iowa

1,084

Community water system

118

Non-transient non-community water system

626

Transient non-community water system

Largest water systems in Iowa

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The largest active public water systems in Iowa by population served
#	Water system	County	Population served	Type	Source
1	Des Moines Water Works	Polk	246,055	Community	Purchased surface water
2	Iowa-American Wtr Co-Davenport	Scott	147,720	Community	Surface water
3	Cedar Rapids Water Department	Linn	142,364	Community	Groundwater under influence of surface water
4	Sioux City Water Supply	Woodbury	85,791	Community	Groundwater under influence of surface water
5	Ankeny, City of	Polk	76,207	Community	Purchased surface water
6	West Des Moines Water Works	Dallas + 1 more	73,959	Community	Purchased surface water
7	Waterloo Water Works	Black Hawk	69,504	Community	Groundwater
8	Iowa City Water Department	Johnson	68,753	Community	Surface water
9	Council Bluffs Water Works	Pottawattamie	64,447	Community	Surface water
10	Dubuque Water Works	Dubuque	59,667	Community	Groundwater
11	Ames Water Treatment Plant	Story	55,177	Community	Groundwater
12	Urbandale Water Utility	Polk	45,605	Community	Purchased surface water
13	Isu	Story	42,000	Community	Purchased groundwater
14	Marion Municipal Water Dept	Linn	41,623	Community	Groundwater
15	Cedar Falls Municipal Water Utilities	Black Hawk	40,713	Community	Groundwater
16	Ia Regional Utilities Assoc (Waverly)	Bremer + 7 more	37,820	Community	Groundwater
17	Rathbun Regional Water Assn (Rathbun)	Decatur + 7 more	33,000	Community	Surface water
18	Waukee Water Supply	Dallas	31,823	Community	Purchased surface water
19	Marshalltown Water Works	Marshall	27,680	Community	Groundwater
20	Mason City Water Department	Cerro Gordo	27,338	Community	Groundwater
21	University Water System	Johnson	26,684	Community	Surface water
22	Burlington Municipal Waterworks	Des Moines	26,015	Community	Surface water
23	Fort Dodge Water Supply	Webster	25,874	Community	Groundwater
24	Ottumwa Water Works	Wapello	25,529	Community	Surface water
25	Muscatine Power & Water	Muscatine	25,516	Community	Groundwater

By county

Johnson125 systems Linn82 systems Scott78 systems Dubuque74 systems Clayton45 systems Winneshiek43 systems Muscatine40 systems Polk38 systems Jones37 systems Allamakee34 systems Cerro Gordo34 systems Pottawattamie33 systems Woodbury32 systems Clinton29 systems Webster29 systems Cedar28 systems Delaware28 systems Kossuth27 systems Jackson26 systems Washington24 systems Benton23 systems Dallas23 systems Fayette23 systems Hardin22 systems Louisa22 systems Wright22 systems Chickasaw21 systems Howard21 systems Story20 systems Buchanan20 systems Franklin20 systems Harrison20 systems Winnebago19 systems Black Hawk18 systems Floyd18 systems Hancock18 systems Mills17 systems Bremer16 systems Butler16 systems Mitchell16 systems Sioux16 systems Cass15 systems Iowa15 systems Calhoun14 systems Dickinson14 systems Monona14 systems Warren14 systems Worth14 systems Carroll13 systems Fremont13 systems Hamilton13 systems Humboldt13 systems Marion13 systems Plymouth13 systems Tama13 systems Boone12 systems Buena Vista12 systems Cherokee12 systems Emmet12 systems Keokuk12 systems Lyon12 systems Marshall12 systems Pocahontas12 systems Des Moines11 systems Henry11 systems Jasper11 systems Crawford10 systems Guthrie10 systems Sac9 systems Page9 systems Palo Alto8 systems Grundy8 systems Jefferson8 systems Poweshiek8 systems Shelby8 systems Lee7 systems Ida7 systems O'Brien7 systems Osceola7 systems Van Buren7 systems Adair6 systems Clay6 systems Decatur5 systems Appanoose5 systems Audubon5 systems Greene5 systems Montgomery5 systems Wapello5 systems Wayne5 systems Madison4 systems Mahaska4 systems Clarke3 systems Ringgold3 systems Taylor3 systems Jo Daviess3 systems Camden3 systems

Adams2 systems

Davis2 systems

Lucas2 systems

Monroe2 systems

Henderson2 systems

Freeborn2 systems

Stone2 systems

Fresno1 systems

Union1 systems

Rock Island1 systems

Peoria1 systems

Delta1 systems

St. Louis1 systems

Sherburne1 systems

Putnam1 systems

Perry1 systems

Morgan1 systems

Midland1 systems