EPA system CA1010007 · California

City of Fresno: PFOS at or above EPA's 4.0 ppt limit

System ID CA1010007; community water system; California; source: surface water; serves 545,716 people via 144,185 connections; status: active

In focus545,716people served, EPA registry

Public records. Clearer context.

City of Fresno is a local-government-owned community water system in California serving about 545,716 people, matched to 21 ZIP codes.

PFAS treatment declared to EPA: Granular activated carbon (7 of 211 sampling events), ozone (4 of 211 sampling events), another treatment (4 of 211 sampling events) · PFAS found before UCMR 5: Yes, at 204 of 378 sampling events

PFAS and lithium: what EPA's national survey found

EPA tested this water for 30 substances and found 10. PFOA averaged 13.5 ppt where EPA's limit is 4.0 ppt, and PFOS averaged 21.5 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 99.1% of the 10,307 water systems EPA tested for it.

Between March 2023 and December 2025, EPA's UCMR 5 program tested 10,151 samples from 174 sampling locations for 30 contaminants (29 PFAS plus lithium). 10 were detected above the reporting level in at least one sample. Averaged over a complete monitoring set, the highest sampling location for PFOA was 13.5 ppt, at or above the MCL of 4.0 ppt that applies from 2029 (highest single sample 16.0 ppt). Averaged over a complete monitoring set, the highest sampling location for PFOS was 21.5 ppt, at or above the MCL of 4.0 ppt that applies from 2029 (highest single sample 30.0 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 204 of 378 sampling events, no at 174 of 378 sampling events; potential PFAS sources nearby: no at 368 of 378 sampling events, yes at 9 of 378 sampling events, not known at 1 of 378 sampling events; PFAS treatment in place: no PFAS treatment at 196 of 211 sampling events, granular activated carbon at 7 of 211 sampling events, ozone at 4 of 211 sampling events, another treatment at 4 of 211 sampling events.

Lead at customer taps

In the latest completed monitoring period, ending Dec 31, 2025, 9 in 10 sampled homes had lead at or below 0 ppb, below the 15 ppb action level that triggers utility action. The action level has been reached in 3 of the 23 periods on record.

In the most recent completed lead monitoring period, ending Dec 31, 2025, the 90th-percentile lead result at customer taps was 0 ppb, below the action level of 15 ppb; 3 of the 23 monitoring periods on record reached the action level. 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: Jun 27, 2025 (site visit); 4 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, 113.8 sq mi