Fremont, California Tap Water Quality Report
Serving utility: Alameda County Water District
Updated March 2026 • Data from EWG Tap Water Database & EPA SDWIS
High Priority Concerns
Fremont tap water has 10 contaminants exceeding EWG health guidelines, including Perfluorohexane sulfonate (PFHXS), Total trihalomethanes (TTHMs), Haloacetic acids (HAA5). Additionally, 9 known or suspected carcinogens were detected, including Total trihalomethanes (TTHMs), Haloacetic acids (HAA5), Haloacetic acids (HAA9).
Water Provider Information
Contaminants Detected
| Contaminant | Detected Level | EWG Guideline | Legal Limit | Status |
|---|---|---|---|---|
| Perfluorohexane sulfonate (PFHXS) | 1.38 ppt | 0.00 ppt | 10 ppt | Above guideline |
| Total trihalomethanes (TTHMs) carcinogen | 41.30 ppb | 0.15 ppb | 80 ppb | Above guideline |
| Haloacetic acids (HAA5) carcinogen | 27.30 ppb | 0.10 ppb | 60 ppb | Above guideline |
| Haloacetic acids (HAA9) carcinogen | 12.60 ppb | 0.06 ppb | No legal limit | Above guideline |
| Bromate carcinogen | 1.18 ppb | 0.10 ppb | 10 ppb | Above guideline |
| Perfluorooctane sulfonate (PFOS) carcinogen | 2.55 ppt | 0.30 ppt | 4 ppt | Above guideline |
| Chromium (hexavalent) carcinogen | 0.14 ppb | 0.02 ppb | No legal limit | Above guideline |
| Nitrate and nitrite carcinogen | 0.33 ppm | 0.14 ppm | 10 ppm | Above guideline |
| Nitrate carcinogen | 0.33 ppm | 0.14 ppm | 10 ppm | Above guideline |
| Chlorate | 222.90 ppb | 210 ppb | No legal limit | Above guideline |
| Chlorodifluoromethane | 0.02 ppb | N/A | No legal limit | Below guideline |
| Fluoride | 0.75 ppm | N/A | 4 ppm | Below guideline |
| Manganese | 1.23 ppb | 100 ppb | No legal limit | Below guideline |
| Molybdenum | 0.40 ppb | 40 ppb | No legal limit | Below guideline |
| Perfluorobutane sulfonate (PFBS) | 1.06 ppt | 2,000 ppt | No legal limit | Below guideline |
| Perfluorobutanoic Acid (PFBA) | 1.04 ppt | 1,000 ppt | No legal limit | Below guideline |
| Perfluorohexanoic Acid (PFHxA) | 0.06 ppt | 1,000 ppt | No legal limit | Below guideline |
| Perfluorooctanoic acid (PFOA) carcinogen | 0.06 ppt | 0.09 ppt | 4 ppt | Below guideline |
| Strontium | 0.20 ppb | 1,500 ppb | No legal limit | Below guideline |
| Vanadium | 0.43 ppb | 21 ppb | No legal limit | Below guideline |
Health Context
Perfluorohexane sulfonate (PFHXS)
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Total trihalomethanes (TTHMs) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Haloacetic acids (HAA5) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Haloacetic acids (HAA9) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Bromate carcinogen
Bromate is a probable human carcinogen that can increase kidney and gastrointestinal cancer risk with chronic exposure. Long-term consumption above 0.010 mg/L (EPA MCL) is associated with increased cancer mortality.
Recommended Filtration for This Water
Echo RO System
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Point-of-use filtration designed to remove heavy metals, lead, arsenic, and PFAS right at your kitchen faucet.
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Shop Hydrogen FlaskFrequently Asked Questions
Is Fremont tap water safe to drink?
Fremont tap water meets EPA legal standards for drinking water. However, 10 contaminants exceed stricter EWG health guidelines, and 9 known carcinogens were detected. While legally compliant, additional filtration is recommended for optimal safety.
What contaminants are in Fremont water?
A total of 20 contaminants were detected in Fremont tap water, including Perfluorohexane sulfonate (PFHXS), Total trihalomethanes (TTHMs). Of these, 10 exceed EWG health guidelines.
What's the best water filter for Fremont?
For Fremont tap water, we recommend a reverse osmosis (RO) system for drinking water — it removes up to 99.9% of contaminants including heavy metals, PFAS, and disinfection byproducts. For shower and bath water, a whole-home filtration system reduces chlorine and volatile organics.
Where does Fremont get its water?
Fremont tap water is provided by Alameda County Water District, serving approximately 344,855 people. For detailed source water information, contact your local utility or visit the EPA's SDWIS database.
Nearby City Water Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: March 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
