State profile · EPA SDWIS + UCMR5
Iowa Drinking Water Quality
1,795 systems serve 3,114,444. Health-based share of the violation record is 20%; SDWIS systems with ≥1 violation: 95.2%.
- 1,795
- SDWIS water systems
- 138,271
- Total violations
- 95.2%
- SDWIS systems w/ a violation
- 21.1%
- UCMR5 PFAS rate (152 tested)
The verdict
20% of 138,271 recorded violations are health-based across 1,795 systems. According to EPA SDWIS population served, Iowa ranks #33 of 66 states and territories by people served through public water systems.
- #33 of 66
- Population · states corpus
- 138,271
- Total EPA violations on record
- 20%
- Health-based (MCL / treatment)
- 95.2%
- SDWIS systems with ≥1 violation
SDWIS violation % and UCMR5 PFAS % use different denominators (full inventory vs tested subset). Population ordinal uses SDWIS population served.
Iowa standing, mid SDWIS violation-rate third
Iowa lands in the middle third by violation rate (95.2%) - enough flagged systems for peer comparisons without matching the densest ledgers. Population served is mid-pack at 3,114,444 (mid served population (≤ 5,131,439)). Health-based share is 20% - a material slice is exposure-relevant, with the rest monitoring or reporting. UCMR5 PFAS detection is 21.1% on the tested subset (mid UCMR5 detection (≤ 35.3%)) - a different denominator from the SDWIS violation rate. Systems listed below are ranked by population served or violation count; pair rate with inventory size before reading exposure scale.
Nationwide similar states
Nearest by SDWIS violation rate
Nearest by population served
Health-based share of this violation record
EPA SDWIS classifications for Iowa's 138,271 recorded violations.
Iowa vs nearest violation-rate peers
Share of SDWIS-listed systems with at least one recorded violation; peers are nearest by absolute rate distance, not a fixed top-seven list.
- IA
Iowa
95.2 % of systems
- MA
Massachusetts
95.2 % of systems
- MO
Missouri
95.4 % of systems
- NJ
New Jersey
95 % of systems
- 05
EPA Region 5 — Tribal Water Systems
94.7 % of systems
What this shows Iowa's rate is 95.2% (1,708 of 1,795 systems; middle-third rate (≤ 96.1%)). This is a comparison of recorded SDWIS violations, not a measure of current water safety.
Iowa vs all jurisdictions by SDWIS system inventory
Where this state's public water system count sits among every state and territory on PlainWater
1,795 26th of 66 higher than 40 of 66 jurisdictions
States and territories, banded by SDWIS-listed public water system count
Each bar is a band; taller bars hold more jurisdictions. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS state aggregates · 2026-05-15
Largest Water Systems
Most Violations
Counties in Iowa
Showing top 30 of 99 counties.
Context: Is your tap water safe? · methodology · all states
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.