Day County, South Dakota — public water systems
At a glance
6 active public water systems are filed under Day County, South Dakota in EPA's SDWIS records, together reporting 2,847 people served. The largest is Webster, which reports serving 1,728 people. All 6 are community water systems serving people where they live.
Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.
Active systems
6
Population served
2.8K
Community systems
6
Groundwater share
33.3%
How does Day County compare with other South Dakota counties?
Day County has the 25th-most active public water systems among the 73 counties listed for active South Dakota systems in EPA records; among the 48 with 3 or more systems, the median has 6. Its systems report 2,847 people served in total, the 38th-largest county figure in the state and 0.3% of the statewide total. The average system here reports serving 475 people, about 66% below the South Dakota average of 1,387. 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 Day County's drinking water come from?
By primary water source, Day County's active systems draw on purchased surface water (4, 67%), purchased groundwater (1, 17%) and groundwater (1, 17%). Overall, 33% rely mainly on groundwater (including purchased groundwater) and 67% on surface water, compared with 76% and 24% across South Dakota. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. The county's largest system, Webster, draws primarily on purchased surface water.
What kinds of water systems operate in Day County?
Day County's active systems break down as 6 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 (100%).
Water systems in Day County
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | Webster | Day | 1,728 | Community | Purchased surface water |
| 2 | Waubay | Day | 473 | Community | Groundwater |
| 3 | Bristol | Day | 288 | Community | Purchased surface water |
| 4 | Roslyn | Day | 181 | Community | Purchased surface water |
| 5 | Pierpont | Day | 129 | Community | Purchased groundwater |
| 6 | Grenville | Day | 48 | Community | Purchased surface water |
Also serving Day County
These systems serve several counties, including Day County. EPA lists another county first for them, so they are not included in the counts above.
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Web Water Development Association | Walworth + 9 more | 20,750 | Community | Surface water |
| Brown-Day-Marshall Rws | Brown + 2 more | 5,673 | Community | Groundwater |
| Clark Rural Water System | Clark + 3 more | 2,325 | Community | Groundwater |
| Clark Rural Water-Kampeska | Codington + 1 more | 602 | Community | Groundwater |
Day County water systems: frequently asked questions
How many public water systems are in Day County, South Dakota?
EPA's SDWIS records file 6 active public water systems under Day County, South Dakota: 6 community systems (100%). At least 4 more systems are listed under another county but also serve Day County.
Who supplies drinking water in Day County, SD?
The largest community water systems filed under Day County are Webster (1,728 people served), Waubay (473 people served) and Bristol (288 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 Day County's drinking water come from groundwater or surface water?
Of the 6 active public water systems in Day County, 33% draw mainly on groundwater and 67% on surface water, counting purchased supplies. The largest system, Webster, uses purchased surface water.
Where can I find a water quality report for Day 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. 6 community systems are filed under Day 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 Day 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 South Dakota 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 Day County, South Dakota”, https://aquacensus.com/water-systems/south-dakota/day (data as of October 1, 2026).