State profile · EPA SDWIS + UCMR5
Oklahoma Drinking Water Quality
1,262 SDWIS-listed systems serve 3,699,452 people. UCMR5 PFAS detection is 36.7% on the tested subset (upper-third UCMR5 detection (> 35.3%)); SDWIS violation rate is 98.2%.
- 1,262
- SDWIS water systems
- 336,706
- Total violations
- 98.2%
- SDWIS systems w/ a violation
- 36.7%
- UCMR5 PFAS rate (166 tested)
The verdict
UCMR5 PFAS detection is 36.7% (61 of 166 tested) - upper-third UCMR5 detection (> 35.3%). According to EPA SDWIS population served, Oklahoma ranks #29 of 66 states and territories by people served through public water systems.
- #29 of 66
- Population · states corpus
- 336,706
- Total EPA violations on record
- 34%
- Health-based (MCL / treatment)
- 98.2%
- SDWIS systems with ≥1 violation
SDWIS violation % and UCMR5 PFAS % use different denominators (full inventory vs tested subset). Population ordinal uses SDWIS population served.
Oklahoma standing, high SDWIS violation-rate third
Oklahoma sits in the upper third of jurisdictions by SDWIS violation rate (98.2%), so the system lists below sample one of the denser state-level compliance trails in this extract. Population served is mid-pack at 3,699,452 (mid served population (≤ 5,131,439)). Health-based share is 34% - a material slice is exposure-relevant, with the rest monitoring or reporting. UCMR5 PFAS detection is 36.7% on the tested subset (upper-third 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 Oklahoma's 336,706 recorded violations.
Oklahoma 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.
- OK
Oklahoma
98.2 % of systems
- MP
Northern Mariana Islands
98.3 % of systems
- 10
EPA Region 10 — Tribal Water Systems
98.1 % of systems
- AZ
Arizona
98.4 % of systems
- AK
Alaska
97.9 % of systems
What this shows Oklahoma's rate is 98.2% (1,239 of 1,262 systems; upper-third rate (> 96.1%)). This is a comparison of recorded SDWIS violations, not a measure of current water safety.
Oklahoma vs all jurisdictions by SDWIS system inventory
Where this state's public water system count sits among every state and territory on PlainWater
1,262 33rd of 66 higher than 33 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 Oklahoma
Showing top 30 of 77 counties.
Context: PFAS in drinking water · 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.