Tapcensus

Water quality for ZIP code 94128

ZIP 94128 covers South San Francisco in San Mateo County, California, one of 30 ZIP codes in the county. 51 active public water systems serve the county; 15 had an EPA violation in the past three years.

Most likely your provider

City of Millbrae CA4110018 · Community water system · Surface water purchased · Millbrae
Serves 22,795 people Rules violated, past 3 years 1 Last sanitary survey Apr 17, 2025 Distance 2.1 mi
View system details EPA facility report

Other community water systems in San Mateo County

35 systems, nearest first
SystemServesStatusRules violated, 3 yrDistance
City of San Bruno
San Bruno		 42,631 0 2.5 mi
City of Burlingame
Burlingame		 32,453 0 3.0 mi
California Water Service-S San Francisco
 62,609 0 3.3 mi
Westborough Water District
 13,486 0 4.0 mi
City of Brisbane
Brisbane		 3,434 0 4.4 mi
Guadalupe Valley Mid
 1,455 0 4.8 mi
Town of Hillsborough
 11,766 0 5.0 mi
North Coast County Water Dist
 38,546 0 5.5 mi
City of Daly City
Daly City		 102,593 0 6.1 mi
California Water Service San Mateo
 103,536 0 6.6 mi
Estero Municipal Improvement District
 36,556 0 8.0 mi
Montara Water and Sanitary District
 6,088 0 8.5 mi
Mid-Peninsula Water District
 31,059 0 9.2 mi
California Water Service San Carlos
 34,801 0 11.0 mi
Coastside County Water District
 19,033 0 11.2 mi
City of Redwood City
Redwood City		 90,043 0 12.7 mi
Menlo Park Municipal Water
Menlo Park		 22,362 0 16.2 mi
California Water Service Bear Gulch
 60,382 0 16.9 mi
Palo Alto Park Mutual Water Company
 2,900 0 17.1 mi
O'connor Tract Co-Operative Water Co.
 2,789 0 17.3 mi
City of East Palo Alto
East Palo Alto		 29,519 0 17.5 mi
Redwood Terrace Mutual
 56 1 22.1 mi
Cuesta la Honda Guild INC
 863 0 22.2 mi
County Service Area 7
 300 1 23.2 mi
Camp Jones Gulch
 44 0 24.3 mi
All 36 community water systems in San Mateo County
Non-community systems in San Mateo County (15: schools, campgrounds, workplaces, restaurants)

These systems serve places you visit rather than homes.

SystemServesStatusRules violated, 3 yrUnresolved
Skylawn Memorial Park (skylawn Inc)
 50 1 1
UC Elkus Ranch
 34 0 0
Martins Beach Water System
 49 1 0
San Gregorio Company
 32 1 0
LA Honda Center
 33 0 0
Optimists Volunteers for Youth
 205 1 0
San Mateo County Memorial Park
 1,790 0 0
Harley Farms Goat Dairy
 113 0 0
Csp Portola State Park
 172 0 0
Butano Girl Scout Camp
 154 0 0
Butano State Park Csp
 121 0 0
Pigeon Point Hostel
 67 1 1
Gazos Creek Beach House
 33 0 0
Costanoa Campground
 33 1 0
Csp Ano Nuevo State Park
 709 0 0
About this data

Water systems are matched to San Mateo County, the county this ZIP code lies in, nearest to the ZIP code's centre first. Your exact provider depends on your address and connection; the largest community water system in a county is usually the city or town utility. Distances are measured to the centre of the service area EPA publishes for the system.

ZIP code areas and town boundaries come from the U.S. Census Bureau's 2020 ZCTA files.

Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The California records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.