Short answer: No measured result is above a legal limit; the water is moderately hard. Alameda County Water District serves 344,000 residents.
Your water bill or annual water quality report names your actual supplier.
Also supplies: Union City, Newark
ALAMEDA COUNTY WATER DISTRICT (EPA PWSID CA0110001) delivers surface water to 344,000 residents. This report reflects 29 individual PFAS result(s) from the source UCMR5 observations and the latest Lead & Copper Rule 90th-percentile result. The utility's 2025 CCR reports moderately hard water.
0health-based violations in the last 10 years
From EPA SDWIS. A clean violation history means no enforcement action was recorded; it does not cover contaminants without a limit.
No result is not a pass. Your utility's annual water quality report may list them, and a certified lab test covers your own tap.
The records describe the system. A certified lab test shows what reaches your glass.
For what was detected in Fremont: Ion-exchange water softener, Salt-free conditioner, Reverse osmosis (point-of-use).
Water treatment technologies →Screening tells you if something is worth a closer look; a lab result is the number you can act on.
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Screening: quick check, not lab-grade
Silver Lake Research
Lead, bacteria, nitrate, copper, iron, chlorine, hardness and pH
What it can't tell you: Each test gives a yes/no or a rough range, not a lab number, and it cannot detect PFAS or arsenic.
Lab-certified results
ETR Laboratories
50+ substances, including lead, copper, arsenic, nitrate, hardness and coliform bacteria
What it can't tell you: It does not test PFAS, and not every result on the panel falls under the lab's accredited scope.
When your results arrive, read them here →
PurityMap does not give a safe/unsafe verdict; it shows what the public records measured. For Fremont, no regulated PFAS were detected in EPA's 2024 testing. ALAMEDA COUNTY WATER DISTRICT (PWSID CA0110001) has a Purity Score of 100/100 (confidence: moderate), assessed at the water-system level and computed only from contaminants that were measured. Water can change in your own pipes, so a certified test is the only way to know what comes out of your tap.
ALAMEDA COUNTY WATER DISTRICT (PWS ID CA0110001) is the public water system on record for Fremont, California, serving about 344,000 people. Confirm the utility on your water bill before acting on a specific finding.
Surface water (primary source of record in EPA SDWIS).
None of the 29 PFAS in EPA's UCMR 5 testing (2024-01-16 to 2024-10-22) was detected. "Not detected" means below the lab's reporting limit, not proven zero.
Lead is not in Fremont's current published record. Lead usually enters from a building's own pipes and fixtures, so a certified home test is the way to know yours.
PurityMap's current record for Fremont holds 32 findings: 1 detected within the reference and 31 not detected. Each finding links to its dated public record; a parameter that was never monitored is shown as pending, not as a pass.
Fremont's water is recorded as 5.2 gpg, moderately hard. Hardness is an aesthetic and plumbing characteristic, not a health-based limit.
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| Contaminant | Result | Benchmark | Status | Sampled | Source |
|---|---|---|---|---|---|
| Water hardness | 5.2 gpg | Aesthetic, no federal health limit | Within a secondary/aesthetic reference | 2025 | Alameda County Water District 2025 Consumer Confidence Report (CCR) |
| Contaminant | Result | Benchmark | Status | Sampled | Source |
|---|---|---|---|---|---|
| 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Lead (90th percentile) | Non-Detect (ND) | 15 µg/L federal action level | Not detected above the reporting limit | 2022–2024 monitoring period | Lead & Copper Rule 90th-percentile: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Lithium | < 9 µg/L | 10 µg/L EPA health reference level (screening, not a legal limit)Screening level, not a legal limit | Not detected above the reporting limit | 2024-01-17 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorobutanesulfonic acid (PFBS) | < 3 ng/L | 2,000 ng/L EPA health advisory (screening, not a legal limit)Screening level, not a legal limit | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorobutanoic acid (PFBA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorohexanesulfonic acid (PFHxS) | < 3 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorohexanoic acid (PFHxA) | < 3 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorooctanesulfonic acid (PFOS) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorooctanoic acid (PFOA) | < 4 ng/L | 4.0 ng/L federal MCL (2024) | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluoropentanoic acid (PFPeA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2024-01-16 to 2024-10-22 | UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001) |
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)
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)
Perfluorobutanesulfonic acid (PFBS)
Perfluorododecanoic acid (PFDoA)
Perfluoroheptanesulfonic acid (PFHpS)
Perfluoroheptanoic acid (PFHpA)
Perfluorohexanesulfonic acid (PFHxS)
Perfluorohexanoic acid (PFHxA)
Perfluorooctanesulfonic acid (PFOS)
Perfluoropentanesulfonic acid (PFPeS)
Perfluoropentanoic acid (PFPeA)
Perfluorotetradecanoic acid (PFTA)
Perfluorotridecanoic acid (PFTrDA)
Perfluoroundecanoic acid (PFUnA)
Every value is the published result from the cited public record. A reporting limit is the lowest level the method could reliably quantify; a non-detect is not a guarantee of zero.
UCMR5 Analytical Results
UCMR5 Analytical Results: ALAMEDA COUNTY WATER DISTRICT (CA0110001)
US EPA
State SDWIS Compliance Record
Lead & Copper Rule 90th-percentile: ALAMEDA COUNTY WATER DISTRICT (CA0110001)
US EPA SDWIS
Consumer Confidence Report (CCR)
Alameda County Water District 2025 Consumer Confidence Report (CCR)
Alameda County Water District
Methodology: how we analyze water. Prepared with AI assistance and reviewed by the PurityMap Editorial Team before publication.
Start with the hot-or-cold tap check. Where Alameda County Water District reported something related, it's shown below.
Lead at Alameda County Water District: not detected (90th percentile, 2022–2024 monitoring period). Lead has no taste, so a taste neither shows nor rules it out.
A ZIP code is a postal area, not a water service area. Your water bill names your supplier.