San Francisco Regional Water System

Our primary water source originates from spring snowmelt flowing down the Tuolumne River into the Hetch Hetchy Reservoir. This protected Sierra water source meets exemption standards from filtration requirements by the USEPA and State Water Resources Control Board Division of Drinking Water (SWRCB-DDW).

Water from Hetch Hetchy undergoes several treatment processes to ensure safety and quality:

• Ultraviolet light and chlorine disinfection
• pH adjustment for optimal corrosion control
• Fluoridation for dental health protection
• Chloramination to maintain disinfectant residuals and minimize byproducts

Hetch Hetchy supplies are supplemented with surface water from two local watersheds:

• The 35,000-acre Alameda Watershed (Calaveras and San Antonio reservoirs)
• The 23,000-acre Peninsula Watershed (Crystal Springs, San Andreas and Pilarcitos reservoirs)

Since mid-2017, we've introduced small amounts of groundwater from local wells to diversify our supply sources and enhance reliability for San Francisco residents. All water from our regional treatment plants undergoes filtration, disinfection, fluoridation, and pH adjustment for corrosion control.

1. Why is my water usage so high? It might not be – meter readings can sometimes be transposed or difficult to read. You may have an undetected leaky toilet or faucet. Contact our office and we'll help resolve the issue.
2. What should I do about low water pressure? First, inspect your meter and surrounding area for potential leaks. Then call our office to report the low pressure in your area.
3. Why does my water appear discolored? Recent repairs may have allowed air to enter the line, creating a milky appearance. This is typically temporary.
4. What chemicals are added to our water? We only use chemicals approved by the National Safety Foundation specifically for municipal water treatment.
5. My water tastes and smells unusual. Is it safe? State law requires all public water systems to maintain minimum chlorine levels of 0.2 mg/L (tested at line endpoints). Systems using chloramine must maintain 0.5 mg/L per federal regulations. We test disinfectant levels daily to ensure safety.
6. Why do particles appear when running hot water? Your water heater likely needs flushing. CAUTION: Manufacturers typically recommend hiring a professional for this maintenance to avoid injury or damage.
7. Will I receive a bill even if I don't use water? Yes, you'll receive a minimum monthly charge of $25.00 for the water service availability.