Alameda County Water Quality: 5 Cities Ranked by the Records
Alameda County, California: 5 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 1 system of 5 tested4.0 ng/L federal MCL (2024) · US EPAHighest26 ng/L
- CITY OF PLEASANTON26 ng/LSample date: 2024-08-20 to 2025-05-15
- ALAMEDA COUNTY WATER DISTRICTNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-01-16 to 2024-10-22
- CITY OF HAYWARDNot detected · below 4.0 ng/L lab reporting limitSample date: 2025-04-02 to 2025-12-15
- CITY OF LIVERMORENot detected · below 4.0 ng/L lab reporting limitSample date: 2025-02-19 to 2025-11-18
- EAST BAY MUDNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-04-04 to 2025-11-18
Perfluorohexanesulfonic acid (PFHxS)Detected in 1 system of 5 tested10 ng/L federal MCL (2024) · US EPAHighest22 ng/L
- CITY OF PLEASANTON22 ng/LSample date: 2024-08-20 to 2025-05-15
- ALAMEDA COUNTY WATER DISTRICTNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-01-16 to 2024-10-22
- CITY OF HAYWARDNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-04-02 to 2025-12-15
- CITY OF LIVERMORENot detected · below 3.0 ng/L lab reporting limitSample date: 2025-02-19 to 2025-11-18
- EAST BAY MUDNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-04-04 to 2025-11-18
LithiumDetected in 1 system of 5 tested10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest16.8 µg/L
- CITY OF PLEASANTON16.8 µg/LSample date: 2024-08-20 to 2025-05-15
- ALAMEDA COUNTY WATER DISTRICTNot detected · below 9.0 µg/L lab reporting limitSample date: 2024-01-17 to 2024-10-22
- CITY OF HAYWARDNot detected · below 9.0 µg/L lab reporting limitSample date: 2025-04-02 to 2025-12-15
- CITY OF LIVERMORENot detected · below 9.0 µg/L lab reporting limitSample date: 2025-02-19 to 2025-11-18
- EAST BAY MUDNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-04-04 to 2025-11-18
Perfluorooctanoic acid (PFOA)Detected in 1 system of 5 tested4.0 ng/L federal MCL (2024) · US EPAHighest5.1 ng/L
- CITY OF PLEASANTON5.1 ng/LSample date: 2024-08-20 to 2025-05-15
- ALAMEDA COUNTY WATER DISTRICTNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-01-16 to 2024-10-22
- CITY OF HAYWARDNot detected · below 4.0 ng/L lab reporting limitSample date: 2025-04-02 to 2025-12-15
- CITY OF LIVERMORENot detected · below 4.0 ng/L lab reporting limitSample date: 2025-02-19 to 2025-11-18
- EAST BAY MUDNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-04-04 to 2025-11-18
Perfluorobutanesulfonic acid (PFBS)Detected in 1 system of 5 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest6.1 ng/L
- CITY OF PLEASANTON6.1 ng/LSample date: 2024-08-20 to 2025-05-15
- ALAMEDA COUNTY WATER DISTRICTNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-01-16 to 2024-10-22
- CITY OF HAYWARDNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-04-02 to 2025-12-15
- CITY OF LIVERMORENot detected · below 3.0 ng/L lab reporting limitSample date: 2025-02-19 to 2025-11-18
- EAST BAY MUDNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-04-04 to 2025-11-18
Perfluorohexanoic acid (PFHxA)Detected in 2 systems of 5 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest4.1 ng/L
- CITY OF PLEASANTON4.1 ng/LSample date: 2024-08-20 to 2025-05-15
- EAST BAY MUD3.5 ng/LSample date: 2023-04-04 to 2025-11-18
- ALAMEDA COUNTY WATER DISTRICTNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-01-16 to 2024-10-22
- CITY OF HAYWARDNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-04-02 to 2025-12-15
- CITY OF LIVERMORENot detected · below 3.0 ng/L lab reporting limitSample date: 2025-02-19 to 2025-11-18
Water hardnessDetected in 3 systemsAesthetic, no federal health limit · USGSHighest5.2 gpg
- ALAMEDA COUNTY WATER DISTRICT5.2 gpgReporting year: 2025
- EAST BAY MUD5.1 gpgReporting year: 2025
- CITY OF HAYWARD3.5 gpgReporting year: 2025
Perfluorobutanoic acid (PFBA)Detected in 2 systems of 5 testedNo federal or state limit; shown for transparencyHighest6.3 ng/L
- CITY OF PLEASANTON6.3 ng/LSample date: 2024-08-20 to 2025-05-15
- EAST BAY MUD5.2 ng/LSample date: 2023-04-04 to 2025-11-18
- ALAMEDA COUNTY WATER DISTRICTNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-01-16 to 2024-10-22
- CITY OF HAYWARDNot detected · below 5.0 ng/L lab reporting limitSample date: 2025-04-02 to 2025-12-15
- CITY OF LIVERMORENot detected · below 5.0 ng/L lab reporting limitSample date: 2025-02-19 to 2025-11-18
2 more contaminants detectedShow
Perfluoropentanesulfonic acid (PFPeS)Detected in 1 system of 5 testedNo federal or state limit; shown for transparencyHighest4.3 ng/L
- CITY OF PLEASANTON4.3 ng/LSample date: 2024-08-20 to 2025-05-15
- ALAMEDA COUNTY WATER DISTRICTNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-01-16 to 2024-10-22
- CITY OF HAYWARDNot detected · below 4.0 ng/L lab reporting limitSample date: 2025-04-02 to 2025-12-15
- CITY OF LIVERMORENot detected · below 4.0 ng/L lab reporting limitSample date: 2025-02-19 to 2025-11-18
- EAST BAY MUDNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-04-04 to 2025-11-18
Perfluoropentanoic acid (PFPeA)Detected in 1 system of 5 testedNo federal or state limit; shown for transparencyHighest4.1 ng/L
- CITY OF PLEASANTON4.1 ng/LSample date: 2024-08-20 to 2025-05-15
- ALAMEDA COUNTY WATER DISTRICTNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-01-16 to 2024-10-22
- CITY OF HAYWARDNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-04-02 to 2025-12-15
- CITY OF LIVERMORENot detected · below 3.0 ng/L lab reporting limitSample date: 2025-02-19 to 2025-11-18
- EAST BAY MUDNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-04-04 to 2025-11-18
22 substances tested, none detected in any systemShow
Tested in these 5 systems: ALAMEDA COUNTY WATER DISTRICT, CITY OF HAYWARD, CITY OF LIVERMORE, CITY OF PLEASANTON, EAST BAY MUD
- 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)
- 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 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)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorononanoic acid (PFNA)
- 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 5 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 California3cities report hardness · hardest Fremont, 5.2 gpg
None above 7 gpg, the USGS threshold for hard water. An aesthetic measure with no federal health limit.
Hard water explainedLargest water systems
- OaklandEAST BAY MUD · CA01100051,468,000 served
- FremontALAMEDA COUNTY WATER DISTRICT · CA0110001344,000 served
- HaywardCITY OF HAYWARD · CA0110006162,954 served
- PleasantonCITY OF PLEASANTON · CA011000876,689 served
- LivermoreCITY OF LIVERMORE · CA011001138,892 served
Frequently asked
How does Alameda County tap water compare across cities?
PurityMap ranks 5 cities in Alameda 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 Oakland's main water system: EAST BAY MUD · PWSID CA0110005 · Purity Score 100 (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 Alameda County cities had a PFAS sample above a 2024 EPA limit?
1 of 5 Alameda County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Pleasanton (PFOS 26 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 2.
Is there lead in Alameda County tap water?
Utilities report lead as a 90th-percentile result from home taps. 0 of 5 Alameda 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.
Does Alameda County have hard water?
Hardness is published in utility water-quality reports for 3 Alameda County cities on record; the hardest is Fremont at 5.2 grains per gallon. Hardness affects scale and appliances; it is not a health finding.
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