Mahaska County, Iowa — public water systems
At a glance
4 active public water systems are filed under Mahaska County, Iowa in EPA's SDWIS records, together reporting 24,159 people served. The largest is Oskaloosa Municipal Water Dept, which reports serving 12,808 people. All 4 are community water systems serving people where they live.
Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.
Active systems
4
Population served
24.2K
Community systems
4
Groundwater share
100%
How does Mahaska County compare with other Iowa counties?
Mahaska County has the 91st-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 24,159 people served in total, the 28th-largest county figure in the state and 0.8% of the statewide total. The average system here reports serving 6,040 people, about 3.5 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 Mahaska County's drinking water come from?
By primary water source, Mahaska County's active systems draw on groundwater (2, 50%), groundwater under influence of surface water (1, 25%) and purchased groundwater under influence (1, 25%). Overall, all rely mainly on groundwater (including purchased groundwater) and none on surface water, compared with 92% and 7.8% across Iowa. Groundwater means the system draws its water from wells or springs fed by underground aquifers. The county's largest system, Oskaloosa Municipal Water Dept, draws primarily on groundwater under influence of surface water.
What kinds of water systems operate in Mahaska County?
Mahaska County's active systems break down as 4 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 (50%) and private (50%).
Water systems in Mahaska County
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | Oskaloosa Municipal Water Dept | Mahaska | 12,808 | Community | Groundwater under influence of surface water |
| 2 | Mahaska Rural Water System, Inc.. | Mahaska | 9,818 | Community | Groundwater |
| 3 | Mahaska Rural Water (New Sharon) | Mahaska | 1,368 | Community | Groundwater |
| 4 | Oak Creek MHP | Mahaska | 165 | Community | Purchased groundwater under influence |
Mahaska County water systems: frequently asked questions
How many public water systems are in Mahaska County, Iowa?
EPA's SDWIS records file 4 active public water systems under Mahaska County, Iowa: 4 community systems (100%).
Who supplies drinking water in Mahaska County, IA?
The largest community water systems filed under Mahaska County are Oskaloosa Municipal Water Dept (12,808 people served), Mahaska Rural Water System, Inc.. (9,818 people served) and Mahaska Rural Water (New Sharon) (1,368 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 Mahaska County's drinking water come from groundwater or surface water?
Of the 4 active public water systems in Mahaska County, all draw mainly on groundwater and none on surface water, counting purchased supplies. The largest system, Oskaloosa Municipal Water Dept, uses groundwater under influence of surface water.
Where can I find a water quality report for Mahaska 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. 4 community systems are filed under Mahaska 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 Mahaska 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 Mahaska County, Iowa”, https://aquacensus.com/water-systems/iowa/mahaska (data as of October 1, 2026).