Tapcensus

Water quality for ZIP code 94070

ZIP 94070 covers San Carlos, Redwood City, and Belmont 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

California Water Service San Carlos CA4110007 · Community water system · Surface water purchased
Serves 34,801 people Rules violated, past 3 years 0 Last sanitary survey Sep 10, 2024 Distance 0.2 mi

Your location is within the outer bounds of this system's EPA service area.

View system details EPA facility report

Other community water systems in San Mateo County

35 systems, nearest first
SystemServesStatusRules violated, 3 yrDistance
Mid-Peninsula Water District
 31,059 0 1.7 mi
City of Redwood City
Redwood City		 90,043 0 2.3 mi
Estero Municipal Improvement District
 36,556 0 4.1 mi
California Water Service San Mateo
 103,536 0 4.3 mi
Menlo Park Municipal Water
Menlo Park		 22,362 0 5.8 mi
Town of Hillsborough
 11,766 0 6.3 mi
Palo Alto Park Mutual Water Company
 2,900 0 7.2 mi
California Water Service Bear Gulch
 60,382 0 7.2 mi
O'connor Tract Co-Operative Water Co.
 2,789 0 7.2 mi
City of East Palo Alto
East Palo Alto		 29,519 0 7.7 mi
City of Burlingame
Burlingame		 32,453 0 8.1 mi
Coastside County Water District
 19,033 0 9.5 mi
City of Millbrae
Millbrae		 22,795 1 10.1 mi
Cuesta la Honda Guild INC
 863 0 12.3 mi
City of San Bruno
San Bruno		 42,631 0 12.5 mi
Redwood Terrace Mutual
 56 1 12.6 mi
Montara Water and Sanitary District
 6,088 0 13.0 mi
County Service Area 7
 300 1 13.3 mi
North Coast County Water Dist
 38,546 0 13.9 mi
California Water Service-S San Francisco
 62,609 0 14.2 mi
Westborough Water District
 13,486 0 14.3 mi
Camp Jones Gulch
 44 0 14.5 mi
City of Brisbane
Brisbane		 3,434 0 15.1 mi
Camp Loma Mar
 25 2 15.2 mi
Guadalupe Valley Mid
 1,455 0 15.5 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
LA Honda Center
 33 0 0
Optimists Volunteers for Youth
 205 1 0
San Gregorio Company
 32 1 0
San Mateo County Memorial Park
 1,790 0 0
Csp Portola State Park
 172 0 0
Harley Farms Goat Dairy
 113 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.