Water quality for ZIP code 94546
ZIP 94546 covers Castro Valley, Hayward, and Ashland in Alameda County, California, one of 49 ZIP codes in the county. 27 active public water systems serve the county; 4 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 Alameda County
13 systems, nearest first| System | Serves | Status | Rules violated, 3 yr | Distance |
|---|---|---|---|---|
| Norris Canyon Property Owners Assn |
50 | 1 | 3.2 mi | |
| Trailer Haven Mobile Home Park |
459 | 0 | 3.6 mi | |
| City of Hayward Hayward |
162,954 | 0 | 5.0 mi | |
| Dublin San Ramon Services District |
98,776 | 0 | 10.0 mi | |
| City of Pleasanton Pleasanton |
76,689 | 0 | 11.4 mi | |
| Sfpuc-Pleasanton Wells |
1 | 0 | 11.8 mi | |
| Alameda County Water District |
344,000 | 0 | 12.9 mi | |
| Alameda Point |
600 | 0 | 13.3 mi | |
| Town of Sunol Sfpuc |
281 | 0 | 13.3 mi | |
| California Water Service Livermore |
60,414 | 0 | 17.1 mi | |
| City of Livermore Livermore |
38,892 | 0 | 17.4 mi | |
| Zone 7 Water Agency |
40 | 0 | 19.8 mi | |
| Castlewood Domestic Water System |
524 | 1 | 25.8 mi |
Non-community systems in Alameda County (13: schools, campgrounds, workplaces, restaurants)
These systems serve places you visit rather than homes.
| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Ebrpd Piedmont Stables |
45 | 0 | 0 | |
|
Alameda County Fairgrounds |
82 | 1 | 1 | |
|
Chp Mission Grade Scales Pleasanton |
1,800 | 1 | 0 | |
|
Sunol Super Stop |
155 | 0 | 0 | |
|
Ebrpd Sunol Regional Wilderness |
91 | 0 | 0 | |
|
Lawrence Livermore National Lab Site 200 Livermore |
10,735 | 0 | 0 | |
|
Ebrpd del Valle Regional Park |
9,024 | 0 | 0 | |
|
Purple Orchid Resort Spa Livermore |
52 | 0 | 0 | |
|
Mountain House Bar |
25 | 0 | 0 | |
|
Mountain House School |
50 | 0 | 0 | |
|
Usbr-Sldmwa Cvp Jones Pumping Plant |
90 | 0 | 0 | |
|
Rivers End Marina |
32 | 0 | 0 | |
|
Rancho los Mochos-Bsa Camp |
38 | 0 | 0 |
About this data
Water systems are matched to Alameda 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.