Mendocino County Water Quality
Mendocino County, California: one city report 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)UKIAH, CITY OF4.0 ng/L federal MCL (2024) · US EPA7.4 ng/L
- UKIAH, CITY OF7.4 ng/LSample date: 2023-01-17 to 2024-08-01
Perfluorooctanoic acid (PFOA)UKIAH, CITY OF4.0 ng/L federal MCL (2024) · US EPA6.9 ng/L
- UKIAH, CITY OF6.9 ng/LSample date: 2023-01-17 to 2024-08-01
Perfluorohexanesulfonic acid (PFHxS)UKIAH, CITY OF10 ng/L federal MCL (2024) · US EPA7.3 ng/L
- UKIAH, CITY OF7.3 ng/LSample date: 2023-01-17 to 2024-08-01
Perfluorobutanesulfonic acid (PFBS)UKIAH, CITY OF2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPA6.2 ng/L
- UKIAH, CITY OF6.2 ng/LSample date: 2023-01-17 to 2024-08-01
Perfluorohexanoic acid (PFHxA)UKIAH, CITY OF400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLE4.4 ng/L
- UKIAH, CITY OF4.4 ng/LSample date: 2023-01-17 to 2024-08-01
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)UKIAH, CITY OFNo federal or state limit; shown for transparency17.8 ng/L
- UKIAH, CITY OF17.8 ng/LSample date: 2023-01-17 to 2024-08-01
Perfluorobutanoic acid (PFBA)UKIAH, CITY OFNo federal or state limit; shown for transparency9.2 ng/L
- UKIAH, CITY OF9.2 ng/LSample date: 2023-01-17 to 2024-08-01
Perfluoroheptanoic acid (PFHpA)UKIAH, CITY OFNo federal or state limit; shown for transparency3.3 ng/L
- UKIAH, CITY OF3.3 ng/LSample date: 2023-01-17 to 2024-08-01
1 more contaminant detectedShow
Perfluoropentanoic acid (PFPeA)UKIAH, CITY OFNo federal or state limit; shown for transparency5.1 ng/L
- UKIAH, CITY OF5.1 ng/LSample date: 2023-01-17 to 2024-08-01
22 substances tested, none detected in this systemShow
Tested in this system: UKIAH, CITY OF
- 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)
- Lithium
- 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)
- Perfluoropentanesulfonic acid (PFPeS)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
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 1 city 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
- UkiahUKIAH, CITY OF · CA231000316,067 served
Frequently asked
How does Mendocino County tap water compare across cities?
PurityMap ranks 1 city in Mendocino 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 Ukiah's main water system: UKIAH, CITY OF · PWSID CA2310003 · Purity Score 61 (Fair) · 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 Mendocino County cities had a PFAS sample above a 2024 EPA limit?
1 of 1 Mendocino County city report had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Ukiah (PFOS 7.4 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 1.
Is there lead in Mendocino County tap water?
Utilities report lead as a 90th-percentile result from home taps. 0 of 1 Mendocino 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.
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