What San Francisco Residents Should Know
San Francisco's drinking water is primarily sourced from the pristine Hetch Hetchy Reservoir in Yosemite National Park, supplemented by local reservoirs in the Alameda and Peninsula watersheds. This water travels approximately 167 miles through a gravity-fed system from the Sierra Nevada Mountains to San Francisco, largely avoiding the need for energy-intensive pumping.
The San Francisco Public Utilities Commission (SFPUC) maintains rigorous quality standards, and the Hetch Hetchy source is so pure that it meets federal drinking water requirements without filtration. The system serves approximately 2.7 million people in the Bay Area, with San Francisco itself receiving the highest quality water in the system.
Despite the high quality source water, San Francisco faces two main water quality challenges. First, the city's many historic buildings and neighborhoods may contain lead service lines or lead plumbing components, presenting risks for buildings constructed before 1986. Second, the aging infrastructure, including some pipes over 100 years old, can occasionally introduce contaminants into the water after treatment.
Key Contaminants Found
These substances have been detected in San Francisco's water supply, though most are at levels well below regulatory limits.
Lead
Below LimitSource: Lead service lines, lead solder in plumbing, and older fixtures in pre-1986 buildings
Health Effects: Developmental delays in children, learning disabilities, reduced IQ, kidney problems, high blood pressure
San Francisco Levels: Average 3.5 ppb (90th percentile), with approximately 2% of samples exceeding the EPA action level
EPA Limit: Action level 15 ppb, but no safe level exists
Total Trihalomethanes (TTHMs)
Below LimitSource: Byproducts formed when chlorine used to disinfect water reacts with organic matter
Health Effects: Potential increased risk of cancer with long-term exposure, liver and kidney problems
San Francisco Levels: 25-40 ppb, varying by location and season
EPA Limit: 80 ppb
Naturally Occurring Minerals
Below LimitSource: Natural mineral content from Sierra Nevada mountains and local watersheds
Health Effects: No health concerns at current levels, some minerals like fluoride have dental health benefits
San Francisco Levels: Low mineral content compared to most U.S. cities, "soft" water with 3.8 grains per gallon
EPA Limit: Varies by mineral, all below regulatory limits
PFAS ("Forever Chemicals")
Very Low LevelsSource: Industrial products, firefighting foam, consumer goods
Health Effects: Increased cholesterol, changes in liver function, decreased vaccine response in children, increased risk of certain cancers
San Francisco Levels: Below 2 ppt combined PFOA/PFOS, among the lowest of major U.S. cities
EPA Limit: 4 ppt for PFOA and PFOS
Neighborhood Variations
Water quality can vary across San Francisco's diverse neighborhoods, primarily due to differences in building age and infrastructure.
Water Quality by Area
| Neighborhood/Area | Risk Level | Water Source | Buildings Pre-1986 | Notable Concerns |
|---|---|---|---|---|
| North Beach/Chinatown | Medium | Hetch Hetchy | 85% | Lead, Aging Infrastructure |
| Mission/Noe Valley | Medium | Hetch Hetchy | 78% | Lead, Aging Infrastructure |
| Western Addition/Hayes Valley | Medium | Hetch Hetchy | 75% | Lead |
| Richmond/Sunset Districts | Low | Hetch Hetchy | 60% | Minimal Concerns |
| Marina/Pacific Heights | Low | Hetch Hetchy | 65% | Minimal Concerns |
| Mission Bay/SOMA | Low | Hetch Hetchy | 25% | Minimal Concerns |
Data based on San Francisco Public Utilities Commission sampling and building age estimates.
Recommended Action Steps
While San Francisco's water is generally of excellent quality, these actions can further protect your household, particularly in older buildings.
Test Your Water If in a Historic Building
If you live in a pre-1986 building, especially in North Beach, Chinatown, Mission, or other older neighborhoods, consider testing your water for lead. The SFPUC offers free lead testing for residents.
Free Lead Testing ProgramRun Cold Water Before Use
In older buildings, run cold water for 30-60 seconds before using it for drinking or cooking, especially in the morning or after being away from home for several hours. This helps flush out any lead that may have leached into water sitting in pipes.
Check for Lead Plumbing
If you live in an older building, check your service line material and interior plumbing for lead components. The SFPUC maintains records for many properties and can help you identify if you have lead service lines or other lead plumbing features.
Lead Plumbing InformationConsider Building-Wide Filtration
If you live in a multi-unit building in an older neighborhood, talk to your building management about whole-building filtration systems. These can be more cost-effective than individual filters in each unit and provide consistent protection for all residents.
Stay Informed About Water Quality
Subscribe to updates from the SFPUC about water quality, including the annual Water Quality Report. This information will help you stay informed about any changes or temporary issues that might affect your tap water.
Water Quality ReportsSupport Water System Maintenance
San Francisco's water infrastructure includes some pipes that are over 100 years old. Support local initiatives to maintain and upgrade this critical infrastructure to ensure continued high water quality for future generations.
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