EPA system OH3102612 · Ohio

Cincinnati Public Water System: PFOS at or above EPA's 4.0 ppt limit

System ID OH3102612; community water system; Ohio; source: surface water; serves 750,200 people via 244,716 connections; status: active

In focus750,200people served, EPA registry

Public records. Clearer context.

Cincinnati Public Water System is a local-government-owned community water system in Ohio serving about 750,200 people, matched to 58 ZIP codes.

PFAS treatment declared to EPA: None declared (6 of 6 sampling events) · PFAS found before UCMR 5: Yes, at 6 of 6 sampling events

PFAS and lithium: what EPA's national survey found

EPA tested this water for 30 substances and found 3. PFOS averaged 5.2 ppt where EPA's limit is 4.0 ppt. EPA's limit applies to a running yearly average and is enforced from 2029. That PFOS result is higher than 93% of the 10,307 water systems EPA tested for it.

Between May 2023 and February 2024, EPA's UCMR 5 program tested 180 samples from 2 sampling locations for 30 contaminants (29 PFAS plus lithium). 3 were detected above the reporting level in at least one sample. Averaged over a complete monitoring set, the highest sampling location for PFOS was 5.2 ppt, at or above the MCL of 4.0 ppt that applies from 2029 (highest single sample 6.1 ppt).

Sampling-point average: mean of a location's two (ground water) or four (surface water) UCMR 5 results with non-detects counted as zero, EPA's method for comparing UCMR 5 data to the PFAS MCLs. EPA rounds to the reference value's significant digits before deciding whether an average is "greater than" an MCL (PFOA/PFOS averages count as above 4.0 ng/L only from 4.05 ng/L; lithium results count as above the 10 ppb reference only from 15 ppb). This site does not apply that rounding: "at or above" here means the measured value is numerically at or above the reference.

Utility-reported context (UCMR 5 questionnaire, aggregated across sampling events): PFAS previously found at this system: yes at 6 of 6 sampling events; potential PFAS sources nearby: yes at 6 of 6 sampling events; PFAS treatment in place: no PFAS treatment at 6 of 6 sampling events.

Lead and copper at customer taps

In the latest completed monitoring period, ending Jun 30, 2026, 9 in 10 sampled homes had lead at or below 2.1 ppb, below the 15 ppb action level that triggers utility action. The action level has been reached in 1 of the 58 periods on record.

In the most recent completed lead monitoring period, ending Jun 30, 2026, the 90th-percentile lead result at customer taps was 2.1 ppb, below the action level of 15 ppb; 1 of the 58 monitoring periods on record reached the action level. 4 further records are excluded here as censored or implausible in EPA's database. The 90th percentile is the value that 9 in 10 sampled homes were at or below. Values are in parts per billion (ppb).

Drinking water violations since Sep 3, 2016

EPA lists no drinking-water violations for this utility since Sep 3, 2016.

EPA's SDWIS database lists no drinking water violations for this utility since Sep 3, 2016.

None on file.

Sanitary surveys and site visits

Most recent state inspection: Apr 11, 2025 (reason not recorded); 3 visits since Sep 3, 2021.

What you can do about these results

ZIP codes served

Sources

Data vintage: EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.

• EPA ECHO detailed facility report
• EPA UCMR 5 Data Finder
• EPA service-area boundary: modeled, 357.2 sq mi