A90/100
South San Francisco Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 13,486 residents · California
What's In South San Francisco's Tap Water?
54
Contaminants Tested
0
Exceed EPA Limits
0
Above EPA Goals
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 1998.
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Water Utility Details
WESTBOROUGH WATER DISTRICT
Population Served
13,486
Water Source
Purchased Surface Water
System ID
CA4110027
Frequently Asked Questions About South San Francisco Water
Is South San Francisco tap water safe to drink?
South San Francisco, California tap water receives a grade of A (90/100), which is considered excellent. Out of 54 contaminants tested, none exceed EPA maximum contaminant levels (MCLs). While the water meets federal standards, some residents may still choose to use a filter for additional peace of mind.
What contaminants are in South San Francisco's water?
54 contaminants were tested in South San Francisco's water supply. No contaminants exceed EPA legal limits (MCLs) or health goals (MCLGs), which is a positive indicator of water quality.
Does South San Francisco have any water quality violations?
Yes, South San Francisco has 2 EPA violation(s) on record, with the most recent in 1998. Violation types include MCL, TT. 2 of these are health-based violations, which are the most serious category.
Do I need a water filter in South San Francisco?
South San Francisco water meets EPA standards, so a filter is not strictly necessary. However, some residents prefer the added security of a water filter. EPA health goals (MCLGs) are stricter than legal limits and are set at levels with zero expected health risk. All contaminants are within health goals.
Where does South San Francisco's tap water come from?
South San Francisco's drinking water is sourced from purchased surface water and supplied by WESTBOROUGH WATER DISTRICT. The system serves approximately 13,486 people. Surface water sources include rivers, lakes, and reservoirs.
How often is South San Francisco's water tested?
Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. South San Francisco's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.
How does South San Francisco's water compare to other cities in California?
South San Francisco's water quality score of 90/100 earns a grade of A, which is considered excellent. This places South San Francisco among the better-performing water systems in California. Visit our California state page to see how all cities in the state compare.
What should I do if I'm concerned about South San Francisco's water quality?
If you have concerns about South San Francisco's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (WESTBOROUGH WATER DISTRICT) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.