Tapcensus

Water quality for ZIP code 94027

ZIP 94027 covers Atherton and West Menlo Park 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 Redwood City CA4110022 · Community water system · Surface water purchased · Redwood City
Serves 90,043 people Rules violated, past 3 years 0 Last sanitary survey Jul 30, 2024 Distance 2.9 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
Menlo Park Municipal Water
Menlo Park		 22,362 0 1.6 mi
O'connor Tract Co-Operative Water Co.
 2,789 0 3.1 mi
Palo Alto Park Mutual Water Company
 2,900 0 3.3 mi
City of East Palo Alto
East Palo Alto		 29,519 0 3.8 mi
California Water Service San Carlos
 34,801 0 4.6 mi
California Water Service Bear Gulch
 60,382 0 6.4 mi
Mid-Peninsula Water District
 31,059 0 6.5 mi
Estero Municipal Improvement District
 36,556 0 7.9 mi
California Water Service San Mateo
 103,536 0 8.9 mi
Cuesta la Honda Guild INC
 863 0 10.0 mi
Redwood Terrace Mutual
 56 1 10.7 mi
County Service Area 7
 300 1 10.9 mi
Town of Hillsborough
 11,766 0 11.1 mi
Camp Jones Gulch
 44 0 12.1 mi
City of Burlingame
Burlingame		 32,453 0 12.8 mi
Camp Loma Mar
 25 2 12.9 mi
Coastside County Water District
 19,033 0 13.2 mi
Portola Improvement Association Mwc
 80 1 13.2 mi
Redwood Glen Camp & Conference Ctr
 31 0 13.5 mi
Loma Mar Mutual
 65 0 13.9 mi
City of Millbrae
Millbrae		 22,795 1 14.8 mi
Butano Canyon Mutual
 150 0 16.5 mi
Bianchi Flowers INC
 65 1 16.7 mi
County Service Area 11
 450 0 17.1 mi
City of San Bruno
San Bruno		 42,631 0 17.2 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
LA Honda Center
 33 0 0
UC Elkus Ranch
 34 0 0
Optimists Volunteers for Youth
 205 1 0
Martins Beach Water System
 49 1 0
San Mateo County Memorial Park
 1,790 0 0
San Gregorio Company
 32 1 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.