Tapcensus

Water quality for ZIP code 94507

ZIP 94507 covers Alamo, Walnut Creek, Castle Hill, and Danville in Contra Costa County, California, one of 43 ZIP codes in the county. 84 active public water systems serve the county; 21 had an EPA violation in the past three years.

Most likely your provider

Contra Costa Water District CA0710003 · Community water system · Surface water
Serves 210,500 people Rules violated, past 3 years 0 Last sanitary survey Jan 13, 2022 Distance 10.0 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 Contra Costa County

38 systems, nearest first
SystemServesStatusRules violated, 3 yrDistance
Wilcox Station Ranch
 31 1 7.8 mi
Moraga Heights Mutual Water
 66 0 7.9 mi
City of Martinez
Martinez		 31,015 0 11.5 mi
Clayton Palms Water
 549 1 12.8 mi
Golden State Water Company Bay Point
 23,765 0 12.8 mi
Bella Vista Water Sys
 93 3 13.4 mi
Riverview Mobile Home Park
 126 1 13.4 mi
City of Pittsburg
Pittsburg		 62,500 0 13.5 mi
Doubletree Ranch Water System
 66 0 14.0 mi
Casa Medanos Water System
 45 1 14.5 mi
City of Antioch
Antioch		 116,781 0 15.2 mi
Brentwood
Brentwood		 64,513 0 17.5 mi
Randall-Bold Water Treatment Plant
 1 0 17.9 mi
Ccwd/brentwood Wtp
 0 0 18.0 mi
Colonia Santa Maria
 32 2 18.4 mi
Big Oak Mobile Home Park Water
 156 0 20.1 mi
Diablo Water District
 47,158 0 20.3 mi
Camino Mobilehome
 210 0 20.7 mi
Knightsen Community Water System
 73 0 21.2 mi
Town of Discovery Bay
 16,790 0 22.9 mi
Dutch Slough Water Works
 49 1 23.0 mi
Angler S Ranch #3
 60 1 23.1 mi
Orwood Resort
 350 2 23.1 mi
Anglers Subdivision 4
 99 1 23.3 mi
Oakley Mutual Water Company
 170 2 23.7 mi
All 39 community water systems in Contra Costa County
Non-community systems in Contra Costa County (45: schools, campgrounds, workplaces, restaurants)

These systems serve places you visit rather than homes.

SystemServesStatusRules violated, 3 yrUnresolved
Old Borges Ranch Water Sys
 75 0 0
Wildwood Acres Resort
 28 0 0
Ebrpd Little Hills
 66 0 0
Mount Diablo State Park
 364 0 0
Concord MT Diablo Trailride Assoc.
 120 0 0
Canyon School
 80 1 1
Ebrpd Old Briones Regional Park
 47 0 0
All Star Academy of Danville
 30 0 0
Willow Pass Bussiness Park Water System
 60 1 1
Ebrpd Black Diamond Mines
 74 0 0
Ebrpd Morgan Territory
 57 0 0
Ebrpd Round Valley Water System
 82 0 0
Ebrpd Bay Point Regional Shoreline
Pittsburg 		105 0 0
McAvoy Yacht Harbor
 55 0 0
Los Vaqueros Marina Bldg
 180 0 0
Bridgehead Cafe
 75 0 0
Los Vaqueros Interpretive Center
 30 0 0
Bethel Missionary Baptist
 54 0 0
Bay Standards
 41 1 1
Byron United Methodist
 50 0 0
Marin Food Specialties
 25 0 0
Country Junction Deli
 200 0 0
Excelsior Middle School
 600 0 0
Byron Roadhouse
 25 0 0
Byron Corners INC
 205 0 0
Byron Airport
 35 0 0
Knightsen Elementary School
 350 0 0
Gas N Save
 120 0 0
Byron Inn
 60 0 0
Tess Farm Market
Brentwood 		25 0 0
New Life Marina
 80 0 0
Dwr Delta Field Division Banks PP
 180 0 0
Delta Sportsman
 150 0 0
Sunset Marina
 30 0 0
Bethel Market
 100 0 0
Delta Bar and Grill
 100 0 0
Bethel Baptist Church
 75 0 0
Bethel Harbor
 45 0 0
Willowest Marina WS
 35 0 0
Brentwood Marina
 30 0 0
Holland Riverside Marina
 45 0 0
Cruiser Haven Marina
 75 0 0
Sugar Barge Marina
 150 0 0
Ebrpd Alhambra
 115 0 0
Wahl Family Water System
 65 0 0
About this data

Water systems are matched to Contra Costa 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.