Tapcensus

Water quality for ZIP code 94028

ZIP 94028 covers Portola Valley, Palo Alto, Ladera, and 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

California Water Service Bear Gulch CA4110006 · Community water system · Surface water
Serves 60,382 people Rules violated, past 3 years 0 Last sanitary survey Feb 20, 2025 Distance 4.7 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
Cuesta la Honda Guild INC
 863 0 5.2 mi
County Service Area 7
 300 1 6.0 mi
Menlo Park Municipal Water
Menlo Park		 22,362 0 6.1 mi
Redwood Terrace Mutual
 56 1 6.2 mi
O'connor Tract Co-Operative Water Co.
 2,789 0 6.7 mi
Camp Jones Gulch
 44 0 7.1 mi
Palo Alto Park Mutual Water Company
 2,900 0 7.1 mi
City of East Palo Alto
East Palo Alto		 29,519 0 7.4 mi
City of Redwood City
Redwood City		 90,043 0 7.9 mi
Portola Improvement Association Mwc
 80 1 7.9 mi
Camp Loma Mar
 25 2 8.0 mi
Redwood Glen Camp & Conference Ctr
 31 0 8.5 mi
California Water Service San Carlos
 34,801 0 8.9 mi
Loma Mar Mutual
 65 0 9.2 mi
Mid-Peninsula Water District
 31,059 0 10.6 mi
Butano Canyon Mutual
 150 0 11.6 mi
Bianchi Flowers INC
 65 1 12.3 mi
Estero Municipal Improvement District
 36,556 0 12.8 mi
County Service Area 11
 450 0 12.9 mi
Oku Incorporated
 35 3 13.1 mi
California Water Service San Mateo
 103,536 0 13.2 mi
Coastside County Water District
 19,033 0 14.4 mi
Marchi Central Farm
 30 2 14.5 mi
Town of Hillsborough
 11,766 0 14.9 mi
City of Burlingame
Burlingame		 32,453 0 16.8 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
LA Honda Center
 33 0 0
Optimists Volunteers for Youth
 205 1 0
San Mateo County Memorial Park
 1,790 0 0
Csp Portola State Park
 172 0 0
San Gregorio Company
 32 1 0
UC Elkus Ranch
 34 0 0
Martins Beach Water System
 49 1 0
Harley Farms Goat Dairy
 113 0 0
Skylawn Memorial Park (skylawn Inc)
 50 1 1
Butano Girl Scout Camp
 154 0 0
Butano State Park Csp
 121 0 0
Gazos Creek Beach House
 33 0 0
Pigeon Point Hostel
 67 1 1
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.