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ZIP Code 94558 Water Quality
California · 1,888 people served · 13 water systems
D
PoorZIP code 94558 is in California and is a rural community from a drinking-water-service perspective, with 1,888 people served by 13 EPA-registered public water systems. It corresponds to NAPA.
Within ZIP code 94558, the EPA Safe Drinking Water Information System (SDWIS) records 8 health-based violations during the past five years across 13 water systems serving this postal area. The grade of D reflects the aggregate compliance pattern, not the current daily water quality.
Last updated: 2026-05-18 · Source: EPA SDWIS
ZIP Code Location
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Cities in ZIP 94558
Water Systems Serving 94558
BERRYESSA PINES WATER SYSTEM
PWSID: CA2810009
261 served
MEYERS WATER CO.
PWSID: CA2800530
250 served
RIVER RANCH FARM WORKER CENTER
PWSID: CA2800035
66 served
CALISTOGA FARM WORKER CENTER
PWSID: CA2800039
65 served
MONDAVI FARM WORKER CENTER
PWSID: CA2800040
66 served
MILTON ROAD WATER COMPANY
PWSID: CA2801080
44 served
LITTLE LAKE MOBILE HOME PARK
PWSID: CA2300705
38 served
SPANISH FLAT WATER DISTRICT
PWSID: CA2810014
230 served
CIRCLE OAKS WATER DISTRICT
PWSID: CA2800521
500 served
R RANCH AT THE LAKE
PWSID: CA2800593
28 served
HESS WINERY
PWSID: CA2801016
250 served
BUCKTAIL MUTUAL WATER COMPANY
PWSID: CA5301001
42 served
EDDY DRIVE
PWSID: CA4901671
48 served
About ZIP-code water data
Postal-code level water quality data is built up from the underlying water systems — multiple ZIPs may share a single utility, and a single ZIP can span multiple utilities. For property-level information, contact the specific utility serving your address. EPA data on this page was last refreshed on 2026-05-18.
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