What's in WESTERN HILLS WATER DISTRICT/DIABLO GRAN's water?
WESTERN HILLS WATER DISTRICT/DIABLO GRAN has a health-based violation on record, but none in the last five years - an older issue, not necessarily a current one. Population served: 2,000, over 596 connections.
WESTERN HILLS WATER DISTRICT/DIABLO GRAN's record against the rest of the country
Out of 12,903 systems in this dataset, WESTERN HILLS WATER DISTRICT/DIABLO GRAN ranks 529th by violation burden (96th percentile) - 45 violations total, 32 health-baseds.
Against the CA average
Among the 803 CA systems in this dataset, the average is 5.8 health-based violations - WESTERN HILLS WATER DISTRICT/DIABLO GRAN's 32 is above that. The clean-record guide covers what a comparison like this can hide.
Most recent violation on record
WESTERN HILLS WATER DISTRICT/DIABLO GRAN's most recent violation on record is dated 2018-01-01, with the most recent health-based one dated 2017-01-01. Last reported to EPA: 06/22/2026.
The concern categories on record
WESTERN HILLS WATER DISTRICT/DIABLO GRAN's flagged contaminants and rule violations, grouped by what they actually mean for a filter choice rather than left as EPA's raw code list:
- Microbial contamination / treatment technique - flagged from: Surface Water Treatment Rule
- Disinfection byproducts - flagged from: TTHM; Total Haloacetic Acids (HAA5)
The most severe category on record is microbial contamination / treatment technique, which points toward a microbial-class filter if you want to address it directly.
What WESTERN HILLS WATER DISTRICT/DIABLO GRAN's record does not cover
This is what WESTERN HILLS WATER DISTRICT/DIABLO GRAN reported to its state primacy agency and EPA under the Safe Drinking Water Act - real regulatory record, not a lab test of your specific tap. Water quality can still change between the meter and the faucet - household plumbing sits outside what a record of 45 logged violations can see. The guide to what this data misses covers that gap.