Decatur County, Iowa — public water systems
At a glance
5 active public water systems are filed under Decatur County, Iowa in EPA's SDWIS records, together reporting 38,411 people served. The largest is Rathbun Regional Water Assn (Rathbun), which reports serving 33,000 people. All 5 are community water systems serving people where they live.
Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.
Active systems
5
Population served
38.4K
Community systems
5
Groundwater share
0%
How does Decatur County compare with other Iowa counties?
Decatur County has the 83rd-most active public water systems among the 114 counties listed for active Iowa systems in EPA records; among the 96 with 3 or more systems, the median has 14. Its systems report 38,411 people served in total, the 19th-largest county figure in the state and 1.2% of the statewide total. The average system here reports serving 7,682 people, about 4.5 times the Iowa average of 1,718. Population figures are what each system reports; people served by more than one system, such as a wholesaler and the town that buys from it, are counted by each.
Where does Decatur County's drinking water come from?
By primary water source, Decatur County's active systems draw on surface water (3, 60%) and purchased surface water (2, 40%). Overall, none rely mainly on groundwater (including purchased groundwater) and all on surface water, compared with 92% and 7.8% across Iowa. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. The county's largest system, Rathbun Regional Water Assn (Rathbun), draws primarily on surface water.
What kinds of water systems operate in Decatur County?
Decatur County's active systems break down as 5 community systems (100%). A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. EPA lists their owner types as local government (60%) and private (40%).
Water systems in Decatur County
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | Rathbun Regional Water Assn (Rathbun) | Decatur + 7 more | 33,000 | Community | Surface water |
| 2 | Lamoni Municipal Utilities | Decatur | 2,029 | Community | Surface water |
| 3 | Leon Water Supply | Decatur | 1,830 | Community | Surface water |
| 4 | Sirwa #3 (Leon) | Decatur | 1,373 | Community | Purchased surface water |
| 5 | Garden Grove Water Supply | Decatur | 179 | Community | Purchased surface water |
Also serving Decatur County
These systems serve several counties, including Decatur County. EPA lists another county first for them, so they are not included in the counts above.
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Sirwa #2 (Creston) | Madison + 7 more | 20,793 | Community | Surface water |
Decatur County water systems: frequently asked questions
How many public water systems are in Decatur County, Iowa?
EPA's SDWIS records file 5 active public water systems under Decatur County, Iowa: 5 community systems (100%). At least 1 more system is listed under another county but also serve Decatur County.
Who supplies drinking water in Decatur County, IA?
The largest community water systems filed under Decatur County are Rathbun Regional Water Assn (Rathbun) (33,000 people served), Lamoni Municipal Utilities (2,029 people served) and Leon Water Supply (1,830 people served). Which system serves a particular address depends on its service area, which EPA's SDWIS records do not include; a water bill or the local utility can confirm it.
Does Decatur County's drinking water come from groundwater or surface water?
Of the 5 active public water systems in Decatur County, none draw mainly on groundwater and all on surface water, counting purchased supplies. The largest system, Rathbun Regional Water Assn (Rathbun), uses surface water.
Where can I find a water quality report for Decatur County?
Each community water system must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1, covering the previous calendar year. 5 community systems are filed under Decatur County, so the report to look for is the one from the system that supplies your address.
How can I check violations for a water system in Decatur County?
Open the system's profile from the list on this page. Each profile shows the most recent Safe Drinking Water Act violations in EPA's records, with plain-English labels and whether each one is resolved. For current compliance status, EPA ECHO is the primary source.
More Iowa water systems
About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Public water systems in Decatur County, Iowa”, https://aquacensus.com/water-systems/iowa/decatur (data as of October 1, 2026).