EPA system WA5338100 · Washington

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

System ID WA5338100; community water system; Washington; source: surface water; serves 118,164 people via 39,118 connections; status: active

In focus118,164people served, EPA registry

Public records. Clearer context.

Kennewick City of is a local-government-owned community water system in Washington serving about 118,164 people, matched to 3 ZIP codes.

PFAS treatment declared to EPA: None declared (8 of 8 sampling events) · PFAS found before UCMR 5: Yes, at 8 of 8 sampling events

PFAS and lithium: what EPA's national survey found

EPA tested this water for 30 substances and found 7. PFOS averaged 10.0 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 96% of the 10,307 water systems EPA tested for it. Lithium reached 9.4 ppb; EPA's health reference level, which is guidance and not a limit, is 10 ppb.

Between February 2023 and January 2024, EPA's UCMR 5 program tested 240 samples from 2 sampling locations for 30 contaminants (29 PFAS plus lithium). 7 were detected above the reporting level in at least one sample. Averaged over a complete monitoring set, the highest sampling location for PFOA was 2.2 ppt, below the MCL of 4.0 ppt that applies from 2029 (highest single sample 4.6 ppt). Averaged over a complete monitoring set, the highest sampling location for PFOS was 10.0 ppt, at or above the MCL of 4.0 ppt that applies from 2029 (highest single sample 11.5 ppt). Lithium reached 9.4 ppb in a single sample, below the health reference level of 10 ppb, which is non-regulatory.

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 8 of 8 sampling events; potential PFAS sources nearby: not known at 8 of 8 sampling events; PFAS treatment in place: no PFAS treatment at 8 of 8 sampling events.

Lead and copper 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 1 of the 13 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; 1 of the 13 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 2 violations since Sep 3, 2016. None is health-based. All concern missed monitoring, reporting or public notices, not the water itself.

EPA's SDWIS database lists 2 violations recorded since Sep 3, 2016: 2 for monitoring or reporting, none health-based.

Sanitary surveys and site visits

Most recent state inspection: Jun 13, 2023 (sanitary survey); 1 visit 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, 40.5 sq mi