Water quality for ZIP code 94531
ZIP 94531 covers Antioch 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
Your location is within the outer bounds of this system's EPA service area.
Other community water systems in Contra Costa County
38 systems, nearest first| System | Serves | Status | Rules violated, 3 yr | Distance |
|---|---|---|---|---|
| Randall-Bold Water Treatment Plant |
1 | 0 | 2.4 mi | |
| Ccwd/brentwood Wtp |
0 | 0 | 2.5 mi | |
| Brentwood Brentwood |
64,513 | 0 | 3.7 mi | |
| Big Oak Mobile Home Park Water |
156 | 0 | 4.5 mi | |
| Diablo Water District |
47,158 | 0 | 4.8 mi | |
| Clayton Palms Water |
549 | 1 | 5.0 mi | |
| Casa Medanos Water System |
45 | 1 | 5.2 mi | |
| Knightsen Community Water System |
73 | 0 | 6.1 mi | |
| Colonia Santa Maria |
32 | 2 | 6.4 mi | |
| Contra Costa Water District |
210,500 | 0 | 6.7 mi | |
| Dutch Slough Water Works |
49 | 1 | 7.4 mi | |
| City of Pittsburg Pittsburg |
62,500 | 0 | 7.5 mi | |
| Angler S Ranch #3 |
60 | 1 | 7.6 mi | |
| Anglers Subdivision 4 |
99 | 1 | 7.7 mi | |
| Bethel Island Mutual Water CO |
123 | 1 | 8.2 mi | |
| Farrar Park Property Owners |
140 | 0 | 8.2 mi | |
| Marina Mobile Manor |
75 | 0 | 8.2 mi | |
| Delta Mutual Water Company |
333 | 1 | 8.4 mi | |
| Willow Park Marina |
380 | 1 | 8.4 mi | |
| Sandmound Mutual |
100 | 2 | 8.4 mi | |
| Oakley Mutual Water Company |
170 | 2 | 8.4 mi | |
| Sandy Point Mobile Home Park |
67 | 2 | 8.5 mi | |
| Riverview Mobile Home Park |
126 | 1 | 9.0 mi | |
| Bella Vista Water Sys |
93 | 3 | 9.0 mi | |
| Orwood Resort |
350 | 2 | 9.1 mi |
Non-community systems in Contra Costa County (45: schools, campgrounds, workplaces, restaurants)
These systems serve places you visit rather than homes.
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.