States → Ohio
State profile · EPA SDWIS + UCMR5
Ohio Drinking Water Quality
4,181 public water systems serve 11,085,226 people across Ohio, with every Safe Drinking Water Act violation and UCMR5 PFAS result on record.
- 4,181
- Water systems
- 288,388
- Total violations
- 90.4%
- Systems w/ a violation
- 59%
- PFAS detection rate
The verdict
Across Ohio, 3,781 of 4,181 water systems (90.4%) carry at least one EPA violation, and 204 of 346 UCMR5-tested systems show PFAS.
- 288,388
- Total EPA violations on record
- 18%
- Health-based (MCL / treatment)
- 90.4%
- Systems with ≥1 violation
- 59%
- UCMR5 PFAS detection rate
Water Systems
4,181
Total Violations
288,388
Violation Rate
90.4%
PFAS Detection
59%
204 of 346 tested
Violation Composition
How Ohio's 288,388 violations break down by type, per EPA SDWIS classification.
Health-based (52,412) Monitoring/Reporting (235,976)
| Metric | Value | Share |
|---|---|---|
| Public water systems | 4,181 | - |
| Population served | 11,085,226 | - |
| Total violations | 288,388 | 100% |
| Health-based violations | 52,412 | 18.2% |
| Systems with violations | 3,781 | 90.4% |
| PFAS detection rate | 204 of 346 | 59% |
Health-based violations indicate the contaminant exceeded an EPA Maximum Contaminant Level (MCL) or treatment-technique requirement. Monitoring/reporting violations indicate procedural issues (missed tests, late reports) - not necessarily a contamination event.
Largest Water Systems
Cleveland Public Water System
Cleveland, OH · 1,308,955 served
Columbus Public Water System
Columbus, OH · 1,305,946 served
Cincinnati Public Water System
Cincinnati, OH · 750,200 served
Toledo City Of
Toledo, OH · 360,000 served
Akron City PWS
Kent, OH · 280,000 served
Montgomery County Water Services 1 PWS
Kettering, OH · 150,207 served
Del-Co Water Company, Inc.
Delaware, OH · 150,000 served
Dayton Public Water System
Dayton, OH · 141,407 served
Clermont Public Water System
Batavia, OH · 133,059 served
Youngstown City PWS
Youngstown, OH · 130,530 served
Butler Co. Water District 2 PWS
Hamilton, OH · 116,572 served
Canton Public Water System
Canton, OH · 107,113 served
Aqua Ohio - Massillon PWS
Massillon, OH · 95,636 served
Montgomery County Water Services 2 PWS
Kettering, OH · 83,033 served
Lake County West Water Subdistrict
Painesville, OH · 78,379 served
Warren County
Lebanon, OH · 78,299 served
Aqua Ohio - Mentor
Mentor, OH · 74,500 served
Rural Lorain Co. Water A
Lagrange, OH · 73,125 served
Elyria Water Department
Lorain, OH · 68,000 served
Lima City
Lima, OH · 65,619 served
Most Violations
#1 Sonrise Church Arcanum
1,786 #2 Frontier Campground Waynesville
1,580 #3 Whispering Winds Mhc Grand Rapids
1,429 #4 Woodbury Apartments PWS Dayton
1,407 #5 Church of Troy Garrettsville
1,144 #6 Victory Christian School Urbana
1,095 #7 Fostoria Mobile Estates Fostoria
1,067 #8 Zion Christian School Millersburg
1,039 #9 Western Reserve Village Akron
950 #10 Cedar Oaks Wellness Center Oregonia
917 #11 Terrace Glen MHP LLC Chardon
905 #12 Hope Community Church of the Nazarene Carroll
873 #13 Dawsons Mobile Home Park PWS Piketon
855 #14 Buckeye Ford Inc London
843 #15 McCartney Mobile Estates MHP 1 Las Vegas
843 Counties in Ohio
Franklin
96 systems · 1,503,985 served
· 5,342 violations
Cuyahoga
11 systems · 1,410,751 served
· 1,166 violations
Hamilton
28 systems · 842,267 served
· 1,480 violations
Montgomery
74 systems · 529,379 served
· 4,724 violations
Summit
214 systems · 467,695 served
· 17,163 violations
Lucas
46 systems · 433,198 served
· 3,569 violations
Butler
22 systems · 378,755 served
· 1,035 violations
Lorain
17 systems · 330,150 served
· 1,534 violations
Stark
182 systems · 314,229 served
· 12,064 violations
Warren
21 systems · 242,137 served
· 4,221 violations
Lake
20 systems · 230,589 served
· 1,095 violations
Mahoning
75 systems · 228,296 served
· 4,611 violations
Delaware
5 systems · 195,368 served
· 521 violations
Clermont
9 systems · 187,400 served
· 1,204 violations
Greene
56 systems · 180,062 served
· 3,157 violations
Trumbull
89 systems · 160,312 served
· 6,699 violations
Licking
88 systems · 129,554 served
· 6,135 violations
Portage
173 systems · 127,607 served
· 9,333 violations
Wood
55 systems · 116,066 served
· 3,536 violations
Medina
63 systems · 115,354 served
· 3,445 violations
Clark
92 systems · 106,745 served
· 9,196 violations
Richland
121 systems · 103,898 served
· 6,673 violations
Fairfield
75 systems · 100,143 served
· 6,414 violations
Miami
57 systems · 94,299 served
· 4,277 violations
Allen
41 systems · 90,674 served
· 3,083 violations
Ashtabula
57 systems · 87,422 served
· 3,578 violations
Wayne
177 systems · 85,031 served
· 10,471 violations
Scioto
17 systems · 83,235 served
· 348 violations
Erie
13 systems · 80,465 served
· 980 violations
Athens
13 systems · 75,476 served
· 1,430 violations
Showing top 30 of 88 counties.
Drinking Water Guides
Frequently Asked Questions
How many water systems are in Ohio? ▼
Ohio has 4,181 public water systems serving approximately 11,085,226 people. These include community water systems, non-transient non-community systems, and transient non-community systems regulated under the Safe Drinking Water Act.
How many drinking water violations are in Ohio? ▼
Ohio has 288,388 total drinking water violations on record, with 52,412 classified as health-based violations. 90.4% of water systems in the state have at least one violation.
Has PFAS been found in Ohio drinking water? ▼
Of 346 water systems tested for PFAS in Ohio, 204 had PFAS detected, a 59% detection rate. PFAS are persistent "forever chemicals" that do not break down in the environment.
What is the violation rate for Ohio water systems? ▼
Ohio's violation rate is 90.4%. This measures the percentage of public water systems that have at least one recorded violation in the EPA SDWIS database, including both health-based and monitoring/reporting violations.
Where does this Ohio water data come from? ▼
All drinking water data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS is the federal database that tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources & Methodology
Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial
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.