San Mateo, CA: 1 Violation - Home Safety Score unavailable
5 ZIP codes · 3 water systems · Updated
Data: EPA SDWIS
Key Facts for San Mateo Residents
- Water systems mapped to your city have 1 violation on record since 2021.
- Average of reported 90th-percentile lead results: 0.0044 mg/L.
- Homes built before 1986: 79% - older plumbing may contain lead solder.
- Health risk index (ZipCheckup composite of CDC data): 9.58.
San Mateo's Water Providers
3 systems shown for San Mateo, CA, from 3 on the federal list.
Overview
We track home safety data for 5 ZIP codes in San Mateo, California, covering 3 community water systems serving approximately 140,535 people. The EPA snapshots used for this build directly map water systems to 4 of 5 ZIP codes.
1 of 4 ZIP codes with a reported violation count in the available EPA record (25%) have recorded EPA violations. The available record reports no health-based violations for this measured scope.
Water Sources
San Mateo water systems draw from: Surface water.
Lead & Copper
- Average of reported 90th-percentile lead results: 0.0044 mg/L (EPA action level: 0.015 mg/L)
- 0 of 4 ZIP codes with known status exceed the EPA lead action level
Radon Risk
5 of 5 ZIP records with known zones are in EPA Radon Zone 2.
The EPA recommends testing all homes regardless of radon zone. County radon zones cannot replace an in-home radon test.
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 2 | 1 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 94404 | — | 1 | 0 | Estero Municipal Improvement District |
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 94401 | — | California Water Service - San Mateo | 102,348 |
| 94402 | — | California Water Service - San Mateo | 102,348 |
| 94403 | — | California Water Service - San Mateo | 102,348 |
All ZIP Codes in San Mateo
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
Reporting periods vary by source. Missing data is shown as unavailable, not as zero.
San Mateo Community Health Snapshot
Source: CDC PLACES (County-level estimates). County health indicators are shown for context only and are not linked to this area's water records.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
What's in San Mateo's Water?
Based on EPA violation records. Check your ZIP code report for system-specific contaminant data.
San Mateo Infrastructure Age
With 79% of homes built before 1986, lead solder in plumbing is a potential concern. Federal law banned lead solder in drinking-water plumbing in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
Pre-1986 homes make up a large part of San Mateo's housing; median build year 1964.
Over half of homes in San Mateo were built before 1986, when federal law began restricting lead solder in drinking-water plumbing. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
San Mateo: Lead Risk & Vulnerable Populations
Why children are most at risk: The CDC states that no safe blood lead level in children has been identified. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
If you have young children or are pregnant, consider testing your home's water - especially if your home was built before 1986.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
San Mateo: NFIP Claim Records and Water-Quality Context
Historical NFIP data for San Mateo contains 125 flood insurance claims. Among claims with payment data, the average reported building, contents, and ICC component sum is $12,929. Among ZIP codes with claim records, 25% have an A- or V-family dominant rated zone recorded in those historical claims. This is not a complete current FEMA property-map inventory.
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.
Claim count does not establish current property risk. Check the exact address in FEMA's current map and obtain a property-specific insurance quote when relevant.
Source: historical FEMA National Flood Insurance Program (NFIP) claim records. No current FEMA property-map designation is asserted.
Deep Dive Reports
Detailed analysis for San Mateo, CA