Castro Valley, CA: 2 Health Violations — 77/100 (2026)
2 ZIP codes · 7 water systems · Updated 2026-06-03
For households in Castro Valley, CA water data shows a consistently above-average safety picture.
How Castro Valley Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Castro Valley Water
- Your city's water systems recorded 4 violations in the past 5 years.
- Average lead level: 0.0032 mg/L.
- Homes built before 1986: 65% — older plumbing may contain lead solder.
- Estimated remediation: $2,700 per household.
- CDC health risk index: 9.67.
Who Supplies Your Water in Castro Valley
Castro Valley, CA is covered by 3 major water utilities out of 7 federally tracked systems, each managing its own pipes, treatment processes, and EPA filings. What a household gets from the tap depends on which provider's system serves that address.
Overview
We track water quality and home safety data for 2 ZIP codes in Castro Valley, California (population ~60,207), covering 7 community water systems serving approximately 2,125,309 people region-wide.
2 of 2 ZIP codes (100%) have recorded EPA violations. 2 health-based violations documented.
Home Safety Score
Average Home Safety Score for Castro Valley: B (77/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Castro Valley water systems draw from: Groundwater.
Lead & Copper
- Average lead level (90th percentile): 0.0032 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 2 (Moderate Risk)
- Zone 1 (High): 0 ZIP codes
- Zone 2 (Moderate): 2 ZIP codes
- Zone 3 (Low): 0 ZIP codes
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Stage 2 DBP Rule | Treatment Technique | 6 | 2 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 94546 | B | 2 | 1 | EAST BAY MUD |
| 94552 | B | 2 | 1 | Norris Canyon Property Owners Assn |
All ZIP Codes in Castro Valley
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
Health Outcomes in Castro Valley
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Top Contaminants in Castro Valley Water
Based on EPA violation records. Check your ZIP code report for system-specific contaminant data.
Housing & Infrastructure in Castro Valley
With 65% of homes built before 1986, lead solder in plumbing is a potential concern. The EPA banned lead solder in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
Heavily weighted toward older construction, Castro Valley's housing stock carries a median build year of 1975. That profile puts a majority of homes in the era when lead-soldered copper plumbing was standard practice.
Over half of homes in Castro Valley were built before 1986, when lead solder was banned. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
Cost Context: What Remediation Means for Castro Valley Homeowners
What does remediation cost in financial context for Castro Valley homeowners? Proportionally very little — the equity share here is low, and addressing documented issues is a manageable planning question rather than a material financial burden.
Remediation costs in Castro Valley are relatively low compared to home values. The $1,450–$4,350 estimated range is a small fraction of median property value. Home values are 74% above the California average.
Lead Exposure Risk for Children in Castro Valley
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
When older housing represents 65% of the local inventory or aggregate readings approach the federal action level, an in-home check becomes the standard way to translate citywide averages into the specific reality of an individual Castro Valley address.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in Castro Valley
Over the multi-decade window covered by the National Flood Insurance Program, Castro Valley has accumulated 36 claims — a total that suggests more than isolated flood exposure. With 100% of ZIP codes in designated flood zones, the water-quality implications of flooding move from hypothetical to periodically relevant: treatment intake can be compromised, wells can be infiltrated, and distribution backflow can occur.
Castro Valley has a moderate flood history with 36 FEMA claims averaging $14,644 per payout. 100% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$2,700</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
Deep Dive Reports
Detailed analysis for Castro Valley, CA