F0/100
WESTERN HILLS WATER DISTRICT/DIABLO GRAN — Water Quality Report 2026
Serving 2,000 people · California
Water Source
Surface Water
County
—
System ID
CA5010039
Violations
44
Contaminant Test Results
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 2018.
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Frequently Asked Questions About WESTERN HILLS WATER DISTRICT/DIABLO GRAN
Is WESTERN HILLS WATER DISTRICT/DIABLO GRAN water safe to drink?
WESTERN HILLS WATER DISTRICT/DIABLO GRAN water receives a grade of F (0/100), which is considered failing. 0 contaminant(s) exceed EPA legal limits and 44 violation(s) are on record. Customers may want to consider using a water filter.
What contaminants has WESTERN HILLS WATER DISTRICT/DIABLO GRAN detected?
4 contaminants were tested in WESTERN HILLS WATER DISTRICT/DIABLO GRAN's water. No contaminants exceed EPA legal limits or health goals, indicating good water quality management.
Does WESTERN HILLS WATER DISTRICT/DIABLO GRAN have any EPA violations?
Yes, WESTERN HILLS WATER DISTRICT/DIABLO GRAN has 44 EPA violation(s) on record, with the most recent in 2018. Violation types include MR, MCL, Other. 32 are health-based violations.
How many people does WESTERN HILLS WATER DISTRICT/DIABLO GRAN serve?
WESTERN HILLS WATER DISTRICT/DIABLO GRAN serves approximately 2,000 people, California.
What type of water does WESTERN HILLS WATER DISTRICT/DIABLO GRAN provide?
WESTERN HILLS WATER DISTRICT/DIABLO GRAN sources its water from surface water. Surface water comes from rivers, lakes, or reservoirs and typically requires more extensive treatment. The utility's system ID is CA5010039.
How does WESTERN HILLS WATER DISTRICT/DIABLO GRAN compare to other utilities in California?
WESTERN HILLS WATER DISTRICT/DIABLO GRAN scores 0/100 with a grade of F (failing). This score suggests significant water quality concerns relative to other utilities. Visit our California state page for a full comparison of water systems.