Data: EPA SDWIS, FEMA NFIP, Census ACS

Water Quality in San Francisco

We track home safety signals for 60 ZIP codes in San Francisco, California. EPA community-water data is directly mapped for 29 ZIP codes and 5 water systems.

The available EPA records report no violations across 29 directly mapped ZIP records with reported counts in San Francisco. This measured subset does not cover ZIP records without a confirmed EPA system mapping.

Water sources: Surface water.

Lead Risk

• Average lead level (90th percentile): 0.0036 mg/L
• 1 of 29 ZIP codes with known status exceed the EPA lead action level
• 79% of housing built before 1986 (when lead solder was banned)
• 50% of housing built before 1950 (when lead pipes were standard)
• Median year built: 1936
• Most common estimated pipe material: Galvanized Steel or Lead
• Lead exposure risk score: 62/100
• Estimated lead service line probability: 22%
• 24 ZIP codes classified as high or very high lead risk

With 79% of homes built before the 1986 lead solder ban, San Francisco residents - especially those in older neighborhoods - should consider testing their tap water for lead. Homes built before 1950 are at the highest risk of having lead service lines.

Housing Age Distribution

408,198 total housing units across 60 ZIP codes:

Flood Risk

FEMA National Flood Insurance Program data for San Francisco:

• 145 flood insurance claims on record
• $2,673,379 sum of reported building, contents, and ICC payment components
• 104 claims with payment data
• 41 claims without reported payment fields
• $25,706 average reported component sum among claims with payment data
• Dominant rated-zone value in historical claims: A (A/V-family)
• 14 of 19 ZIP codes with claim-zone records have an A/V-family dominant rated zone in those claims
• Claim-zone values are historical insurance records, not a complete current FEMA property-map inventory

Radon Risk

Dominant EPA radon zone among 60 ZIP records with zone data: 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.

What San Francisco Residents Can Do

Test Your Water

• Order a certified lab test - home test kits cost $20–50 and cover lead, bacteria, and common contaminants
• Request your utility's CCR (Consumer Confidence Report) - your water provider must publish this annually
• Check your ZIP code - each area in San Francisco has different water systems and risk levels

Filter Your Water

• NSF-certified pitcher filter removes chlorine taste and some contaminants ($20–40)
• NSF 53-certified filter for lead - recommended for homes built before 1986
• Reverse osmosis system removes 95%+ of contaminants including lead, PFAS, and nitrates ($150–400)

Test for Radon

• San Francisco is in a moderate-risk radon area
• Short-term radon test kits cost $10–25
• If levels exceed 4 pCi/L, EPA recommends professional mitigation

Stay Informed

• Visit your ZIP code report for detailed, address-level data
• Sign up for EPA water quality alerts
• Review the annual water quality report from your local utility

All ZIP Codes in San Francisco

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

Frequently Asked Questions

Does San Francisco have lead in the water?

The average 90th-percentile lead level across San Francisco is 0.0036 mg/L, below the EPA action level of 0.015 mg/L. 1 of 29 ZIP codes with known action-level status exceed the EPA limit. About 79% of housing was built before 1986, when lead solder was banned.

Is San Francisco at risk for flooding?

FEMA data shows 145 flood insurance claim records in San Francisco ZIP codes, with an average reported building, contents, and ICC component sum of $25,706 among 104 claims with payment data. 41 claims lack reported payment fields and are not counted as zero. Among 19 ZIP codes with historical claim-zone values, 14 have an A/V-family dominant rated zone in those claims. Claim records do not establish current property-level flood risk; check the FEMA map for a specific address.

Are there lead pipes in San Francisco homes?

79% of San Francisco housing was built before 1986, when lead solder was common in plumbing. 50% was built before 1950, when lead pipes were standard. The most common estimated pipe material is Galvanized Steel or Lead. The estimated probability of lead service lines is 22%. We recommend testing your water if your home was built before 1986.

Data Sources

• Water quality: EPA Safe Drinking Water Information System (SDWIS)
• Lead/copper: EPA Lead and Copper Rule sampling data
• Housing age: U.S. Census Bureau American Community Survey
• Flood data: FEMA National Flood Insurance Program
• Lead exposure: Composite risk score based on housing age, water lead levels, and service line estimates
• Radon: EPA Map of Radon Zones

Source reporting periods vary. See each cited source for its publication schedule.

Housing Age Profile

The year 1986 marks a critical threshold in residential plumbing safety: that's when the federal government banned lead solder from new construction, closing a major pathway for lead entering household drinking water via pipe joints. San Francisco's median build year of 1936 signals that most of the city's housing was built under the newer standard. The distribution above tells the full story - the post-1986 majority lowers aggregate risk, but the pre-1986 share still deserves scrutiny from anyone living in or purchasing an older home.

1936

Median Year Built

0%

Pre-1986 (Lead Paint Risk)

0%

Pre-1970 (Lead Pipes Risk)

Most homes in San Francisco were built after 1986, reducing the risk of lead contamination from plumbing. Older homes should still be tested.

Source: U.S. Census Bureau ACS B25034.

Protecting Children from Lead in San Francisco

1 of 60

ZIPs Over EPA Lead Limit

0.0036

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.

<strong>1 ZIP code</strong> (2% of the city) exceeds the EPA lead action level of 0.015 mg/L.

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

Historical Flood-Claim Evidence for San Francisco

145

Total FEMA Flood Claims

$25,706

Avg Reported Sum With Payment Data

74%

A/V Share of Claim-Record ZIPs

Historical NFIP data for San Francisco contains 145 flood insurance claims. Among claims with payment data, the average reported building, contents, and ICC component sum is $25,706. Among ZIP codes with claim records, 74% 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.