San Lorenzo, CA Water Safety: 73/100 (2026)
1 ZIP code · 3 water systems · Updated 2026-06-03
Compared to statewide averages in CA, San Lorenzo scores well — health violations are below the norm and systems generally operate within federal standards.
How San Lorenzo Compares
Data: EPA SDWIS Last verified: 2026-06-03
Key Facts for San Lorenzo Residents
- Homes built before 1986: 89% — older plumbing may contain lead solder.
- Estimated remediation: $1,700 per household.
- CDC health risk index: 9.67.
San Lorenzo's Water Providers
With 3 utilities splitting service in San Lorenzo, CA, water accountability is distributed across 3 systems on the federal record.
Overview
We track water quality and home safety data for 1 ZIP code in San Lorenzo, California (population ~28,866), covering 3 community water systems serving approximately 1,606,174 people region-wide.
No EPA violations recorded across any ZIP codes in San Lorenzo — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for San Lorenzo: B (73/100)
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
San Lorenzo water systems draw from: Groundwater.
Lead & Copper
- Lead data: not yet available for San Lorenzo
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 94580 | B | EAST BAY MUD | 1,442,800 |
All ZIP Codes in San Lorenzo
- 94580 [B]
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.
San Lorenzo Community Health Snapshot
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
San Lorenzo Infrastructure Age
With 89% 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
The character of San Lorenzo's housing stock is one of deep historical layering — a median build year of 1955 signals a city built largely before the plumbing era changes of 1986 and 1970. Lead-soldered copper joints and, in the oldest properties, lead service lines are commonly present in this inventory. That context shapes what individual water testing may reveal, particularly in neighborhoods where the oldest housing is concentrated.
Over half of homes in San Lorenzo 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.
How Remediation Costs Compare in San Lorenzo
Across San Lorenzo, the equity share taken up by estimated remediation is small — a favorable ratio for most property owners.
Remediation costs in San Lorenzo are relatively low compared to home values. The $1,100–$2,600 estimated range is a small fraction of median property value. Home values are 11% above the California average.
San Lorenzo: Lead Risk & Vulnerable Populations
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.
Despite citywide averages serving as the standard public reference point, those aggregates cannot resolve what is happening at one specific faucet — and where 89% of San Lorenzo homes come from before the solder rule or where utility samples sit at or above the action mark, the gap between system data and faucet reality matters more than it does in lower-exposure communities. An in-home draw closes that gap, with certified filtration through retailer networks available where confirmed faucet results warrant additional measures.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
San Lorenzo: Flood History & Water Damage Risk
Across the NFIP's long tracking period, San Lorenzo shows 4 claims and 100% of ZIP codes within FEMA-designated flood zones — figures that place it in moderate flood exposure territory. At this level, the water-quality implications of flooding — contaminated wells, stressed treatment intake, distribution backflow — move from theoretical edge cases to genuine periodic risks, particularly during higher-severity events.
San Lorenzo has a moderate flood history with 4 FEMA claims averaging $2,459 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>$1,700</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 San Lorenzo, CA