Merced County Water Quality: 6 Cities Ranked by the Records
Merced County, California: 6 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
Highest result for each contaminant
One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.
Perfluorooctanesulfonic acid (PFOS)Detected in 3 systems of 6 tested4.0 ng/L federal MCL (2024) · US EPAHighest45 ng/L
- CITY OF ATWATER45 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF MERCED8.9 ng/LSample date: 2023-07-13 to 2024-09-19
- DELHI CWD7.3 ng/LSample date: 2025-05-05 to 2025-11-18
- CITY OF LIVINGSTONNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- WINTON WATER & SANITARY DISTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
Perfluorooctanoic acid (PFOA)Detected in 2 systems of 6 tested4.0 ng/L federal MCL (2024) · US EPAHighest33 ng/L
- CITY OF ATWATER33 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF MERCED6.1 ng/LSample date: 2023-07-13 to 2024-09-19
- CITY OF LIVINGSTONNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- DELHI CWDNot detected · below 4.0 ng/L lab reporting limitSample date: 2025-05-05 to 2025-11-18
- WINTON WATER & SANITARY DISTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
Perfluorohexanesulfonic acid (PFHxS)Detected in 3 systems of 6 tested10 ng/L federal MCL (2024) · US EPAHighest59 ng/L
- CITY OF ATWATER59 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF MERCED15 ng/LSample date: 2023-07-13 to 2024-09-19
- DELHI CWD8 ng/LSample date: 2025-05-05 to 2025-11-18
- CITY OF LIVINGSTONNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- WINTON WATER & SANITARY DISTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
LithiumDetected in 1 system of 6 tested10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest43.6 µg/L
- CITY OF LOS BANOS43.6 µg/LSample date: 2024-09-16 to 2025-03-20
- CITY OF ATWATERNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-10-31 to 2024-05-07
- CITY OF LIVINGSTONNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF MERCEDNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-07-13 to 2024-09-19
- DELHI CWDNot detected · below 9.0 µg/L lab reporting limitSample date: 2025-05-05 to 2025-11-18
- WINTON WATER & SANITARY DISTNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
Perfluorobutanesulfonic acid (PFBS)Detected in 1 system of 6 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest7.8 ng/L
- CITY OF ATWATER7.8 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF LIVINGSTONNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- CITY OF MERCEDNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-07-13 to 2024-09-19
- DELHI CWDNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-05-05 to 2025-11-18
- WINTON WATER & SANITARY DISTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
Perfluorohexanoic acid (PFHxA)Detected in 2 systems of 6 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest25 ng/L
- CITY OF ATWATER25 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF MERCED4.8 ng/LSample date: 2023-07-13 to 2024-09-19
- CITY OF LIVINGSTONNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- DELHI CWDNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-05-05 to 2025-11-18
- WINTON WATER & SANITARY DISTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)Detected in 1 system of 6 testedNo federal or state limit; shown for transparencyHighest13 ng/L
- CITY OF ATWATER13 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF LIVINGSTONNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- CITY OF MERCEDNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-07-13 to 2024-09-19
- DELHI CWDNot detected · below 5.0 ng/L lab reporting limitSample date: 2025-05-05 to 2025-11-18
- WINTON WATER & SANITARY DISTNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
Perfluorobutanoic acid (PFBA)Detected in 1 system of 6 testedNo federal or state limit; shown for transparencyHighest11 ng/L
- CITY OF ATWATER11 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF LIVINGSTONNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- CITY OF MERCEDNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-07-13 to 2024-09-19
- DELHI CWDNot detected · below 5.0 ng/L lab reporting limitSample date: 2025-05-05 to 2025-11-18
- WINTON WATER & SANITARY DISTNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
3 more contaminants detectedShow
Perfluoroheptanoic acid (PFHpA)Detected in 1 system of 6 testedNo federal or state limit; shown for transparencyHighest12 ng/L
- CITY OF ATWATER12 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF LIVINGSTONNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- CITY OF MERCEDNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-07-13 to 2024-09-19
- DELHI CWDNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-05-05 to 2025-11-18
- WINTON WATER & SANITARY DISTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
Perfluoropentanesulfonic acid (PFPeS)Detected in 1 system of 6 testedNo federal or state limit; shown for transparencyHighest8.2 ng/L
- CITY OF ATWATER8.2 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF LIVINGSTONNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- CITY OF MERCEDNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-07-13 to 2024-09-19
- DELHI CWDNot detected · below 4.0 ng/L lab reporting limitSample date: 2025-05-05 to 2025-11-18
- WINTON WATER & SANITARY DISTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
Perfluoropentanoic acid (PFPeA)Detected in 1 system of 6 testedNo federal or state limit; shown for transparencyHighest27 ng/L
- CITY OF ATWATER27 ng/LSample date: 2023-10-31 to 2024-05-07
- CITY OF LIVINGSTONNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-12-12 to 2024-06-18
- CITY OF LOS BANOSNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-09-16 to 2025-03-20
- CITY OF MERCEDNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-07-13 to 2024-09-19
- DELHI CWDNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-05-05 to 2025-11-18
- WINTON WATER & SANITARY DISTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-01 to 2023-11-14
20 substances tested, none detected in any systemShow
Tested in these 6 systems: CITY OF ATWATER, CITY OF LIVINGSTON, CITY OF LOS BANOS, CITY OF MERCED, DELHI CWD, WINTON WATER & SANITARY DIST
- 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
- 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
- 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
- 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
- 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
- Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
- Lead (90th percentile)
- N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
- N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
- Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
- Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
- Perfluoro-3-methoxypropanoic acid (PFMPA)
- Perfluoro-4-methoxybutanoic acid (PFMBA)
- Perfluorodecanoic acid (PFDA)
- Perfluorododecanoic acid (PFDoA)
- Perfluoroheptanesulfonic acid (PFHpS)
- Perfluorononanoic acid (PFNA)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
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Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.
0of 6 cities above the 15 µg/L action level
Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.
Lead in CaliforniaLargest water systems
Frequently asked
How does Merced County tap water compare across cities?
PurityMap ranks 6 cities in Merced County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Los Banos's main water system: CITY OF LOS BANOS · PWSID CA2410005 · Purity Score 97 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.
How many Merced County cities had a PFAS sample above a 2024 EPA limit?
3 of 6 Merced County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Atwater (PFOS 45 ng/L), Merced (PFOS 8.9 ng/L), Delhi (PFOS 7.3 ng/L). That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. PFAS were detected at any level in 3.
Is there lead in Merced County tap water?
Utilities report lead as a 90th-percentile result from home taps. 0 of 6 Merced County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.
Have Merced County water systems had drinking-water violations?
1 city in Merced County has a health-based violation in the federal SDWIS record within about the last ten years. Each city report lists the contaminant, year and whether it was resolved.
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