San Francisco, CA: middle-tier water safety by the latest federal monitoring.

Data: EPA SDWIS Last verified: 2026-06-03

Water Quality Map: San Francisco, CA

Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.

A B C D F

Overview

We track water quality and home safety data for 60 ZIP codes in San Francisco, California, covering 7 community water systems serving approximately 836,321 people.

60 of 60 ZIP codes (100%) have recorded EPA violations. 360 health-based violations documented.

Home Safety Score

Average Home Safety Score for San Francisco: C (55/100)

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 Francisco water systems draw from: Groundwater, Surface water.

Lead & Copper

• Average lead level (90th percentile): 0.0030 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): 60 ZIP codes
• Zone 3 (Low): 0 ZIP codes

The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.

Top Contaminants

Areas with Most Violations

All ZIP Codes in San Francisco

• 94101 [D] — 7 violations ⚠
• 94102 [C] — 7 violations ⚠
• 94103 [C] — 7 violations ⚠
• 94104 [C] — 7 violations ⚠
• 94105 [C] — 7 violations ⚠
• 94107 [C] — 7 violations ⚠
• 94108 [C] — 7 violations ⚠
• 94109 [C] — 7 violations ⚠
• 94110 [C] — 7 violations ⚠
• 94111 [D] — 7 violations ⚠
• 94112 [D] — 7 violations ⚠
• 94114 [C] — 7 violations ⚠
• 94115 [C] — 7 violations ⚠
• 94116 [D] — 7 violations ⚠
• 94117 [D] — 7 violations ⚠
• 94118 [C] — 7 violations ⚠
• 94119 [D] — 7 violations ⚠
• 94120 [C] — 7 violations ⚠
• 94121 [C] — 7 violations ⚠
• 94122 [C] — 7 violations ⚠
• 94123 [C] — 7 violations ⚠
• 94124 [C] — 7 violations ⚠
• 94125 [D] — 7 violations ⚠
• 94126 [D] — 7 violations ⚠
• 94127 [C] — 7 violations ⚠
• 94128 [D] — 7 violations ⚠
• 94129 [D] — 7 violations ⚠
• 94130 [D] — 7 violations ⚠
• 94131 [C] — 7 violations ⚠
• 94132 [C] — 7 violations ⚠
• 94133 [C] — 7 violations ⚠
• 94134 [D] — 7 violations ⚠
• 94136 [D] — 7 violations ⚠
• 94137 [D] — 7 violations ⚠
• 94139 [D] — 7 violations ⚠
• 94140 [D] — 7 violations ⚠
• 94141 [D] — 7 violations ⚠
• 94142 [D] — 7 violations ⚠
• 94143 [D] — 7 violations ⚠
• 94144 [D] — 7 violations ⚠
• 94145 [D] — 7 violations ⚠
• 94146 [D] — 7 violations ⚠
• 94147 [D] — 7 violations ⚠
• 94150 [D] — 7 violations ⚠
• 94151 [D] — 7 violations ⚠
• 94153 [D] — 7 violations ⚠
• 94154 [D] — 7 violations ⚠
• 94156 [D] — 7 violations ⚠
• 94158 [D] — 7 violations ⚠
• 94159 [D] — 7 violations ⚠
• 94160 [D] — 7 violations ⚠
• 94161 [D] — 7 violations ⚠
• 94162 [D] — 7 violations ⚠
• 94163 [D] — 7 violations ⚠
• 94164 [D] — 7 violations ⚠
• 94171 [D] — 7 violations ⚠
• 94172 [D] — 7 violations ⚠
• 94175 [D] — 7 violations ⚠
• 94177 [D] — 7 violations ⚠
• 94188 [D] — 7 violations ⚠

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 Francisco: Remediation Cost in Perspective

Setting San Francisco remediation figures against its property market, the resulting ratio sits comfortably in the low tier — a classification that reflects the kind of household financial position where most homeowners can identify documented issues, schedule the work, and absorb the cost without it registering as a significant budget disruption.

Median Home Value

$1.5M

Est. Remediation

$1,560

Remediation as % of home value 0.1%

Remediation costs in San Francisco are relatively low compared to home values. The $675–$3,122 estimated range is a small fraction of median property value. Home values are 103% above the California average.

Protecting Children from Lead in San Francisco

0.003

mg/L Avg Lead (Limit: 0.015)

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.

Lead risk in San Francisco appears low overall, but individual homes may differ. Testing is the only way to confirm your water's lead content.

Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.

Climate-Related Water Risk for San Francisco

Taken together, San Francisco's 145 NFIP flood insurance claims and 32% FEMA flood zone coverage place it in the moderate range of exposure. That middle position has specific implications for water quality. The contamination pathways that flooding can open — surface water overwhelming treatment facility intake, floodwaters infiltrating private wells, distribution pressure changes creating backflow — are not constant risks in a moderate-exposure community. But they do become active during significant flood events, and the claim record here indicates enough of those events to make flood timing an occasional factor in local water quality conversations.

145

Total FEMA Flood Claims

$16,307

Avg Claim Payout

32%

ZIPs in FEMA Flood Zones

~7

Est. Claims/Year

San Francisco has a moderate flood history with 145 FEMA claims averaging $16,307 per payout. 32% 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>$1,560</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.