Tapcensus

Water quality for ZIP code 94509

ZIP 94509 covers Antioch and Pittsburg 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

City of Antioch CA0710001 · Community water system · Surface water · Antioch
Serves 116,781 people Rules violated, past 3 years 0 Last sanitary survey Jan 17, 2024 Distance 1.4 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
Casa Medanos Water System
 45 1 2.4 mi
Randall-Bold Water Treatment Plant
 1 0 4.3 mi
Ccwd/brentwood Wtp
 0 0 4.4 mi
City of Pittsburg
Pittsburg		 62,500 0 4.9 mi
Contra Costa Water District
 210,500 0 5.4 mi
Big Oak Mobile Home Park Water
 156 0 6.2 mi
Riverview Mobile Home Park
 126 1 6.3 mi
Bella Vista Water Sys
 93 3 6.3 mi
Diablo Water District
 47,158 0 6.4 mi
Brentwood
Brentwood		 64,513 0 6.6 mi
Clayton Palms Water
 549 1 7.1 mi
Knightsen Community Water System
 73 0 8.1 mi
Golden State Water Company Bay Point
 23,765 0 8.3 mi
Angler S Ranch #3
 60 1 8.6 mi
Dutch Slough Water Works
 49 1 8.8 mi
Anglers Subdivision 4
 99 1 8.9 mi
Colonia Santa Maria
 32 2 9.3 mi
Bethel Island Mutual Water CO
 123 1 9.5 mi
Farrar Park Property Owners
 140 0 9.5 mi
Marina Mobile Manor
 75 0 9.7 mi
Sandmound Mutual
 100 2 9.8 mi
Willow Park Marina
 380 1 9.9 mi
Sandy Point Mobile Home Park
 67 2 10.0 mi
Delta Mutual Water Company
 333 1 10.0 mi
Oakley Mutual Water Company
 170 2 10.2 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
Bridgehead Cafe
 75 0 0
Ebrpd Black Diamond Mines
 74 0 0
Bethel Missionary Baptist
 54 0 0
Concord MT Diablo Trailride Assoc.
 120 0 0
Gas N Save
 120 0 0
New Life Marina
 80 0 0
Knightsen Elementary School
 350 0 0
McAvoy Yacht Harbor
 55 0 0
Ebrpd Bay Point Regional Shoreline
Pittsburg 		105 0 0
Delta Sportsman
 150 0 0
Bethel Market
 100 0 0
Delta Bar and Grill
 100 0 0
Sunset Marina
 30 0 0
Willowest Marina WS
 35 0 0
Bethel Baptist Church
 75 0 0
Ebrpd Round Valley Water System
 82 0 0
Bethel Harbor
 45 0 0
Bay Standards
 41 1 1
Mount Diablo State Park
 364 0 0
Willow Pass Bussiness Park Water System
 60 1 1
Brentwood Marina
 30 0 0
Sugar Barge Marina
 150 0 0
Tess Farm Market
Brentwood 		25 0 0
Country Junction Deli
 200 0 0
Byron Roadhouse
 25 0 0
Los Vaqueros Interpretive Center
 30 0 0
Ebrpd Morgan Territory
 57 0 0
Excelsior Middle School
 600 0 0
Holland Riverside Marina
 45 0 0
Byron United Methodist
 50 0 0
Old Borges Ranch Water Sys
 75 0 0
Marin Food Specialties
 25 0 0
Byron Corners INC
 205 0 0
Los Vaqueros Marina Bldg
 180 0 0
Cruiser Haven Marina
 75 0 0
Byron Inn
 60 0 0
All Star Academy of Danville
 30 0 0
Byron Airport
 35 0 0
Ebrpd Old Briones Regional Park
 47 0 0
Wildwood Acres Resort
 28 0 0
Dwr Delta Field Division Banks PP
 180 0 0
Ebrpd Little Hills
 66 0 0
Canyon School
 80 1 1
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.