Oklahoma Water Systems with Most Unresolved Health-Based Violations — 2026
Oklahoma community water utilities ranked by open federal health-based drinking water violations in EPA's SDWIS enforcement records, with demographic context from the Census American Community Survey.
ranked
with demographic data
vintage
boundaries (March 2026)
These 50 Oklahoma water utilities carry the most open federal health-based violations in EPA's enforcement records. Sorted by unresolved count; demographic context from the U.S. Census is shown alongside but is not a ranking input.
| Rank | Water System | State | Pop served | Unresolved health violations | Health viol. (5yr) | % PoC served | % Below 200% FPL | Last violation |
|---|---|---|---|---|---|---|---|---|
| 1 | Muskogee Company RWD #5 | Oklahoma | 4,161 | 45 | 45 | 45% | 43% | 2025-10-01 |
| 2 | Hugo Municipal Authority | Oklahoma | 4,293 | 43 | 46 | 45% | 49% | 2025-07-01 |
| 3 | Southern Okla Water Corporation | Oklahoma | 9,998 | 32 | 32 | 35% | 37% | 2025-07-01 |
| 4 | Tecumseh Utility Authority | Oklahoma | 4,826 | 31 | 31 | 28% | 39% | 2025-09-29 |
| 5 | Coweta PWA | Oklahoma | 6,194 | 29 | 33 | 31% | 27% | 2025-10-01 |
| 6 | Marshall County Rural Water District #2 | Oklahoma | 5,059 | 29 | 29 | 33% | 41% | 2025-07-01 |
| 7 | Adamson RWD #8 | Oklahoma | 4,330 | 25 | 25 | 35% | 40% | 2024-10-01 |
| 8 | Poteau PWA | Oklahoma | 6,674 | 24 | 25 | 30% | 44% | 2025-10-01 |
| 9 | Okmulgee Company RWD #6 (Hectorville) | Oklahoma | 6,323 | 22 | 22 | 30% | 27% | 2025-04-01 |
| 10 | Okmulgee | Oklahoma | 11,316 | 21 | 23 | 46% | 48% | 2025-10-01 |
| 11 | Wagoner Company RWD #4 | Oklahoma | 24,876 | 20 | 29 | 33% | 23% | 2025-07-01 |
| 12 | Kingfisher | Oklahoma | 4,655 | 17 | 17 | 25% | 27% | 2025-10-01 |
| 13 | Altus | Oklahoma | 15,763 | 16 | 20 | 40% | 39% | 2025-04-01 |
| 14 | Rogers Company RWD # 3 Lake Plant | Oklahoma | 24,464 | 16 | 16 | 30% | 25% | 2025-07-01 |
| 15 | Perry Water & Light Department | Oklahoma | 4,079 | 12 | 17 | 13% | 32% | 2025-07-01 |
| 16 | Mcalester PWA | Oklahoma | 7,162 | 12 | 16 | 33% | 40% | 2025-10-01 |
| 17 | Leflore Company RWD #14 | Oklahoma | 7,353 | 10 | 10 | 31% | 47% | 2023-04-01 |
| 18 | Comanche Company RWD #4 | Oklahoma | 4,938 | 8 | 9 | 31% | 30% | 2025-09-29 |
| 19 | Jefferson Company Cons RWD #1 | Oklahoma | 8,202 | 8 | 8 | 20% | 40% | 2023-01-01 |
| 20 | Bryan County Rural Water District #5 | Oklahoma | 7,648 | 6 | 6 | 33% | 42% | 2023-01-01 |
| 21 | Chickasha Municipal Authority | Oklahoma | 14,635 | 5 | 13 | 26% | 38% | 2024-10-17 |
| 22 | Shawnee Municipal Authority | Oklahoma | 28,941 | 5 | 5 | 31% | 38% | 2025-10-01 |
| 23 | Duncan Public Utilities Authority | Oklahoma | 7,515 | 5 | 5 | 24% | 40% | 2025-11-01 |
| 24 | Claremore | Oklahoma | 13,274 | 4 | 8 | 33% | 31% | 2024-01-01 |
| 25 | Mccurtain Company RWD #1 | Oklahoma | 4,031 | 4 | 5 | 43% | 52% | 2024-10-17 |
| 26 | Dewey Public Works Authority | Oklahoma | 7,526 | 4 | 4 | 30% | 44% | 2024-10-17 |
| 27 | Muskogee | Oklahoma | 7,108 | 3 | 5 | 49% | 46% | 2024-01-01 |
| 28 | Stillwater Utilities Authority | Oklahoma | 44,704 | 2 | 8 | 27% | 42% | 2024-01-01 |
| 29 | Craig Company RWD #2 | Oklahoma | 4,707 | 2 | 3 | 39% | 45% | 2025-01-01 |
| 30 | Creek Company RWD # 1 | Oklahoma | 3,753 | 2 | 3 | 26% | 34% | 2025-06-30 |
| 31 | El Reno | Oklahoma | 10,257 | 1 | 9 | 35% | 41% | 2024-10-17 |
| 32 | Stickross Mountain Water Company | Oklahoma | 3,369 | 1 | 9 | 56% | 42% | 2025-10-01 |
| 33 | Creek Company RWD # 2 | Oklahoma | 11,196 | 1 | 5 | 32% | 30% | 2025-01-01 |
| 34 | Tahlequah PWA | Oklahoma | 14,866 | 1 | 3 | 58% | 43% | 2024-10-17 |
| 35 | Osu Water Plant | Oklahoma | 4,082 | 1 | 3 | 30% | 43% | 2025-07-01 |
| 36 | Sequoyah Co. RWD #8 | Oklahoma | 8,040 | 1 | 2 | 40% | 46% | 2025-04-01 |
| 37 | Rogers Company RWD # 4 | Oklahoma | 6,807 | 1 | 2 | 29% | 27% | 2024-10-17 |
| 38 | Sapulpa Rural Water Company | Oklahoma | 4,381 | 1 | 2 | 29% | 34% | 2025-10-01 |
| 39 | Hinton | Oklahoma | 3,701 | 1 | 2 | 37% | 37% | 2025-10-01 |
| 40 | Bartlesville | Oklahoma | 35,959 | 1 | 1 | 28% | 33% | 2025-07-01 |
| 41 | Guymon | Oklahoma | 11,398 | 1 | 1 | 69% | 43% | 2025-01-01 |
| 42 | Grady Company RWD #6 | Oklahoma | 11,300 | 1 | 1 | 18% | 23% | 2025-01-01 |
| 43 | Grove Municipal Services Authority | Oklahoma | 8,636 | 1 | 1 | 27% | 34% | 2024-01-01 |
| 44 | Mayes Company RWD #4 | Oklahoma | 7,910 | 1 | 1 | 35% | 40% | 2025-07-01 |
| 45 | Custer County RWD #3 | Oklahoma | 7,297 | 1 | 1 | 43% | 38% | 2024-10-17 |
| 46 | Washington Company RWD #2 | Oklahoma | 6,580 | 1 | 1 | 28% | 28% | 2024-10-17 |
| 47 | Stephens Company RWD #5 | Oklahoma | 6,537 | 1 | 1 | 22% | 38% | 2025-11-20 |
| 48 | Wagoner | Oklahoma | 6,077 | 1 | 1 | 36% | 36% | 2024-10-17 |
| 49 | Cotton Company RWD #2 | Oklahoma | 4,735 | 1 | 1 | 31% | 35% | 2024-10-17 |
| 50 | Mayes Company RWD # 5 | Oklahoma | 4,636 | 1 | 1 | 34% | 39% | 2025-07-01 |
How to read this ranking
Each row links to a full utility profile with violation history, lead testing results, and service-area ZIPs. The demographic context columns are from independent data sources (ACS, not EJScreen) and are provided for readers who want to examine equity patterns alongside the operational data.
See the full methodology for calculation details, data vintages, and known limitations.
Frequently asked questions
What is an unresolved health-based violation?
A violation of a federal Safe Drinking Water Act standard (Maximum Contaminant Level, Treatment Technique, or Monitoring requirement for a health-based contaminant) that has not been formally returned to compliance in EPA records. These reflect ongoing public-health concerns documented in EPA's ECHO enforcement database.
Why show demographic context next to violations?
Federal Safe Drinking Water Act data does not distinguish between communities by race or income — violations are violations regardless of who is served. We publish demographic columns so readers can independently examine whether specific systems with long-running violations also serve disproportionately low-income or non-white populations. We do not claim causation; we report two independent facts side by side.
Are these the most dangerous water systems in the country?
Not necessarily. "Unresolved" counts procedural and technical violations alongside contaminant exceedances. A high count indicates a system that federal regulators have flagged repeatedly without resolution. For any specific system, click through to its profile page for the individual violations on record.
Where does the data come from?
Violation records come from EPA's Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database, refreshed weekly. Demographic context comes from the U.S. Census American Community Survey (ACS) 5-year estimates (2019-2023), aggregated from block-group level to utility-level using EPA's Community Water System Service Area Boundaries v3 population weights.
ZipCheckup is an independent public-data tool. We are a referral service and do not provide water testing, remediation, or utility services. Rankings reflect publicly-available federal data and are provided for informational purposes. For issues with your specific water system, contact your local water utility or state drinking water program.