San Francisco – California
San Francisco, renowned for its iconic landmarks and environmental leadership, delivers pristine water to over 2.7 million residents across the Bay Area through the San Francisco Public Utilities Commission (SFPUC). The city’s water system includes approximately 1,300 miles of local distribution mains, multiple treatment facilities, and an extensive regional delivery network spanning from the Sierra Nevada mountains to the Pacific Coast.
San Francisco’s drinking water comes primarily from the Tuolumne River watershed in the Sierra Nevada, transported 167 miles via gravity through the Hetch Hetchy system. This mountain snowmelt provides some of the purest municipal water in the United States, requiring minimal treatment. The city also maintains local groundwater sources and reservoirs for emergency backup. San Francisco has invested heavily in seismic resilience, green infrastructure, and water conservation, achieving one of the lowest per capita water consumption rates among major U.S. cities.
San Francisco Water Quality: Current Status (2024-2025)
Latest Testing Results
- Lead Levels: The most recent testing period (January-December 2023) showed 90th percentile lead levels of less than 1 part per billion (ppb), significantly below the EPA action level of 15 ppb, reflecting excellent source water quality and modern infrastructure.
- Testing Scope: SFPUC conducts over 100,000 water quality tests annually, including real-time monitoring at treatment facilities and throughout the distribution network, with enhanced testing for lead in older neighborhoods.
- Compliance Status: San Francisco’s water meets or exceeds all federal and state drinking water standards, consistently ranking among the highest quality municipal water systems in California and nationwide.
Sierra Nevada Source Water
- Hetch Hetchy System: Over 85% of San Francisco’s water comes from the Tuolumne River in Yosemite National Park, providing exceptionally pure mountain snowmelt that travels 167 miles via gravity-fed aqueducts.
- Minimal Treatment Required: The pristine Sierra Nevada source water typically requires only chlorination for disinfection, with fluoridation added for dental health, making it among the least processed municipal water in America.
- Protected Watershed: The entire Tuolumne River watershed is protected from development, with strict land use controls and habitat restoration programs ensuring long-term water quality.
Seismic and Climate Resilience
- Earthquake Preparedness: The $4.8 billion Water System Improvement Program has seismically retrofitted critical infrastructure, including pipelines, treatment facilities, and reservoirs to withstand major earthquakes.
- Emergency Water Supply: Strategic water reserves and emergency interties with neighboring utilities ensure continued service during disasters, with citywide emergency cisterns for firefighting.
- Climate Adaptation: Advanced water recycling, groundwater banking, and watershed management help the system adapt to changing precipitation patterns and ensure long-term sustainability.
Conservation Leadership
- Per Capita Excellence: San Francisco residents use just 42 gallons per person per day, among the lowest in the nation, achieved through comprehensive conservation programs and water-efficient infrastructure.
- Groundwater Management: The city is developing local groundwater resources to reduce reliance on imported water, with new treatment facilities planned in the Westside and Sunset districts.
- Smart Water Technology: Advanced metering infrastructure, leak detection systems, and customer portal tools help residents track usage and quickly identify leaks.
Zero Waste Goals
San Francisco’s water system exemplifies the city’s commitment to environmental sustainability, with initiatives including plastic bottle reduction programs, water bottle filling stations throughout the city, and public education campaigns promoting tap water consumption. The SFPUC operates advanced recycled water facilities that provide non-potable water for irrigation and industrial uses, helping preserve pristine Sierra Nevada water for drinking. These efforts position San Francisco as a global leader in sustainable urban water management while maintaining exceptional water quality standards.
Recommendations for San Francisco Residents
Drink Tap Water
San Francisco’s tap water from the Sierra Nevada is among the purest in the world. Carry a reusable water bottle and use public water fountains throughout the city to stay hydrated sustainably.
Monitor Your Usage
Use the Water Smart portal to track your water consumption, set conservation goals, and receive leak alerts. San Francisco offers rebates for water-efficient fixtures and appliances.
Emergency Preparedness
Store emergency water supplies (1 gallon per person per day for at least 3 days) for earthquake preparedness. Know the location of your nearest emergency cistern.
Older Building Residents
If you live in a building constructed before 1987, run water for 30 seconds before drinking if it’s been sitting for 6+ hours. Consider testing for lead through SFPUC’s free testing program.
Skip Bottled Water
San Francisco’s award-winning tap water is superior to most bottled water. Use the city’s network of public water fountains and filling stations throughout parks, schools, and public buildings.
Frequently Asked Questions
Why is San Francisco’s water considered so pure?
San Francisco’s water quality is exceptional because it comes primarily from the Sierra Nevada mountains in Yosemite National Park. Mountain snowmelt naturally filters through granite and other rocks, removing contaminants and adding beneficial minerals. The water travels 167 miles via gravity-fed aqueducts to the city, requiring minimal treatment.
The protected Tuolumne River watershed has no upstream development or industrial activity, ensuring source water remains pristine. San Francisco typically only adds chlorine for disinfection and fluoride for dental health, making it among the least processed municipal water in America. Independent testing consistently shows our tap water equals or exceeds the quality of premium bottled water.
How well is San Francisco prepared for a major earthquake?
San Francisco has invested $4.8 billion in earthquake-proofing its water system to withstand a magnitude 7.9 earthquake. Key preparedness measures include:
• Seismic retrofitting of all major pipelines, treatment plants, and reservoirs
• 170 emergency cisterns strategically located for firefighting
• Backup power generators at all critical facilities
• Emergency interties with neighboring water systems
• Portable treatment systems for rapid deployment
The system is designed to restore service to most areas within 30 days after a major earthquake, with emergency water available immediately through the cistern network and predetermined emergency distribution points.
Should I be concerned about fluoride in the water?
San Francisco adds fluoride to drinking water at optimal levels (0.7-1.2 mg/L) as recommended by the California Department of Public Health for dental health benefits. This practice has been safely used for over 70 years nationwide.
The American Dental Association, American Medical Association, and Centers for Disease Control all recognize water fluoridation as a safe and effective public health measure. The levels used in San Francisco are well within EPA guidelines and are monitored continuously.
If you prefer, you can use a reverse osmosis filter to remove fluoride, though this also removes beneficial minerals. NSF-certified carbon filters, which remove chlorine taste and odor, do not remove fluoride.
How does climate change affect San Francisco’s water supply?
Climate change poses challenges through:
• Changing snowpack: Earlier snowmelt and reduced snow accumulation in the Sierra Nevada
• Drought cycles: More frequent and severe drought conditions
• Extreme weather: Increased flood and fire risks
San Francisco is adapting through:
• Developing local groundwater resources
• Expanding water recycling programs
• Enhanced reservoir management
• Advanced water conservation programs
• Regional collaboration with other Bay Area utilities
These measures ensure reliable water supply through 2040 and beyond, even under climate change scenarios.
Contaminants of Concern
Chlorine
Source: Added as a disinfectant to prevent bacterial growth in the distribution system
Health Effects: Chlorine at drinking water levels is safe for consumption; some people may be sensitive to taste and odor
Current Status: Maintained at minimal levels due to pristine source water; easily removed by refrigeration or basic carbon filters
Fluoride
Source: Added by SFPUC at optimal levels (0.7-1.2 mg/L) for dental health benefits
Health Effects: Prevents tooth decay in children and adults; levels are carefully controlled to meet California Department of Public Health guidelines
Current Status: Continuously monitored and maintained within safe ranges; supported by major health organizations