Castro Valley, CA
EAST BAY MUD · Serves 1.4M people · Surface Water
contaminants
detected
exceed
guidelines
PFAS
chemicals
Most concerning
Nitrate
2913×health limit
TraceAlso detected: strontium, manganese, Chromium (total), PFBA, vanadium, Gross beta, molybdenum (+7 more contaminants)
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The truth about legal limits
Legal does not equal safe.
Meeting EPA legal limits does not mean your water is safe for drinking.
We benchmark against the strictest independent health-based guidelines.
All Contaminants
17Filter by health risk
Critical findings — every contaminant in your water that exceeds the EWG health limit by 10× or more. Start here.
Filtration Analysis
Viven
Multi-stage
Activated
Carbon filter
Reverse
Osmosis only
PFAS / Forever Chemicals
Viven
99.9%Carbon
PartialRO only
YesHeavy Metals
Viven
99.9%Carbon
LimitedRO only
YesRadionuclides
Viven
99.9%Carbon
NoRO only
YesMinerals re-added
Viven
YesCarbon
NoRO only
NoContaminants in your water that Viven removes
Reserve nowFrequently asked
Castro Valley water quality questions
- Is tap water in Castro Valley, CA (ZIP 94552) safe to drink?
- Tap water for ZIP 94552, served by EAST BAY MUD, has 9 contaminants detected above independent EWG health guidelines, including Nitrate at 2913× the guideline. Meeting EPA legal limits does not necessarily mean water is safe — federal legal limits are often far higher than the latest health-based guidelines.
- What contaminants are in Castro Valley, CA tap water?
- EPA monitoring data for ZIP 94552 shows 17 contaminants detected, including Nitrate, HAA9, Arsenic, HAA5, HAA6Br, Lead. Each detected level is compared against both EPA legal limits and the stricter EWG health guidelines.
- Does Castro Valley, CA tap water have PFAS ("forever chemicals")?
- Yes — 1 PFAS compound was detected out of 30 tested for ZIP 94552. PFAS are persistent synthetic chemicals linked to cancer, immune effects, and developmental harm, with no safe level of exposure established.
- How can I remove these contaminants from my drinking water?
- A multi-stage filtration system that combines activated carbon, reverse osmosis, and remineralization removes PFAS, heavy metals, and disinfection byproducts while restoring beneficial minerals. The Viven faucet is engineered to remove 99.9% of the contaminants found in tap water.
- Where does this Castro Valley, CA water quality data come from?
- This report is built from U.S. EPA data: the Unregulated Contaminant Monitoring Rule (UCMR 3/4/5), the Six-Year Review (SYR4), the Lead and Copper Rule (LCR), and SDWIS violation records. Detected levels are compared against EPA legal limits and Environmental Working Group (EWG) health guidelines. Data last updated 2026-05-01.
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