How many water violations are in Seneca County?

Seneca County has 5,533 total drinking water violations across 64 water systems, of which 882 are health-based violations. 95.3% of systems have at least one violation.

How many people get water from Seneca County systems?

Water systems in Seneca County serve approximately 47,390 people through 64 public water systems.

Has PFAS been detected in Seneca County water?

Under EPA UCMR5, 0 of 2 tested systems in Seneca County had at least one PFAS detection (0.0% of the UCMR5-tested subset - not of all 64 SDWIS systems).

What types of water sources supply Seneca County?

Water systems in Seneca County use GW (60 systems), SW (4 systems) as their primary water sources.

Are health-based violations serious?

Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 15.9% of Seneca County's violations are health-based. Among counties with any SDWIS violations, this extract puts Seneca County in the middle health-based share band. Not all violations indicate immediate health risk, but they require corrective action.

Where does Seneca County sit among U.S. counties for water-system population?

According to EPA SDWIS county population served used on /counties, Seneca County ranks #989 of 3,254 counties by people served, and #44 of 88 counties in Ohio. Ordinals use the same total_population DESC sort as the counties directory. See /methodology#corpus-placement.

Counties → Ohio

Seneca County, Ohio

Compiled by PlainWater · May 15, 2026

SDWIS compliance plate

Sheet OH147 · Seneca County 64 sys · 5,533 viol · #989/3254

VIOL-SEVERE · HEALTH-LOW · RANK-UPPER · PHOTO-FINISH · PFAS-CLEAN · SRC-GW · SYS-MID · BOOK-FULL

VIOL-SEVERE 95.3% flagged
HEALTH-LOW 15.9% health
RANK-UPPER #989/3254
PHOTO-FINISH ±0.0 pp
PFAS-CLEAN 0.0% detect
SRC-GW GW lead 94%
SYS-MID 64 systems
BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Williams County (+ 0 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Seneca County ranks #989 of 3,254 counties by people served, and #44 of 88 counties in Ohio. See methodology · corpus placement.

Seneca County standing, mid-flagged corpus third

Flagged-system rate 95.3% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 15.9% is health-based share in the middle third (≤ 24.5%) . UCMR5 detect rate 0.0% is UCMR5 detect rate at or below the tested-pool lower third (≤ 0.0%) . Population served ranks #989 of 3,254 · #44 of 88 in Ohio.

Water Systems

System Name	Population	Violations	PFAS
Aqua Ohio - Tiffin	20,035	42	Clean
Fostoria City	13,441	43	Clean
Green Springs Village	1,592	157	-
Attica Village	1,148	412	-
Bloomville Village	956	90	-
Hopewell-Loudon School	890	0	-
Bettsville Village	692	118	-
All Saints Catholic Church	590	8	-
Republic Village	550	42	-
New Riegel Local School	524	51	-
Meadowbrook Park Campground 2	428	13	-
Old Fort High School	315	48	-
S and G Store #77	300	3	-
Fostoria Mobile Estates	281	1,067	-
Walnut Grove Campground No 1	233	65	-
New Riegel Cafe	227	30	-
Dollar General Store - Bettsville #14997	225	0	-
Tiffin Drive-in Theater	210	39	-
American Legion Post 354- New Riegel	200	53	-
Clinton Lake Camping 2	200	88	-
The Corner Restaurant	200	12	-
Hopewell-Loudon Athletic Complex	200	9	-
Meadowbrook Park Campground 1	198	8	-
Clinton Heights Golf Course	180	37	-
Old Fort United Methodist Church	179	0	-
Walnut Grove Campground No 2	153	61	-
Camp Glen	152	133	-
I C Treats	150	4	-
Lindsey-Shook Funeral Home	150	8	-
Seneca Country Market	150	67	-
Walnut Grove Campground No 3	136	91	-
Evergreen Poplar Village MHP	128	178	-
Meadowbrook Park-Pool	126	4	-
Eci Inc Corporate Office	125	51	-
Mohawk Golf and Country Club	125	17	-
Loudon Meadows Golf Course	112	45	-
NW Ohio Christian Youth Camp 1	100	70	-
NW Ohio Christian Youth Camp 2	100	15	-
New Riegel Pub	100	51	-
Hopewell-Loudon School Gym Complex	100	48	-
Guru Junction	100	59	-
The Front Nine	100	52	-
Old Fort School Athletic Complex	100	115	-
All Saints Parish Hall	100	4	-
Clinton Lake Camping 1	87	99	-
Tiffin Loader Crane Company	85	150	-
Brook Park Estates MHP	75	350	-
First Christian Church	75	94	-
Fostoria Estates MHP	65	359	-
Walts Tavern	65	57	-

Compare beyond Ohio

Mid-flagged peers for Seneca County

Cross-state counties nearest Seneca County on flagged-system share (95.3%) and cumulative violation count (5,533). In-state neighbours stay on the compliance plate above.

Similar flagged-system rate

Nearest cross-state counties by % of SDWIS systems with at least one violation on record.

4 peers

Similar violation load

Nearest cross-state counties by cumulative SDWIS violation count (all systems in the county).

4 peers

Read our methodology · Check your water system - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater

Compiled by PlainWater, Drinking Water Quality Editorial Process · May 15, 2026

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.