Western Hills Water District/Diablo Gran
Published drinking-water records and contacts for Western Hills Water District/Diablo Gran. System CA5010039. Review sources and dates; not a real-time water assessment.
- System ID
- CA5010039
- State or territory
- CA
- Published population served
- 2000
- System type (source code)
- CWS
Published records and dates
- Lead and copper monitoring summaries: 26 — 1998-01-01 – 2025-12-31
- California DDW laboratory results: 459 — 2026-01-07 – 2026-07-08
Missing records here do not mean the provider did not test. Published records are not a real-time assessment of your tap water.
Published testing results
Selected recent records are shown below. Different sampling locations and dates are not interchangeable. These excerpts are not a complete testing history.
“<” means below the stated reporting limit, not zero. A reported measurement alone is not a safety verdict. Read an example
Lead and copper: 90th-percentile summaries
These describe a monitoring period across sampled locations, not the result at your home. How to read the 90th percentile
| Substance | Published 90th percentile | Monitoring period | Source quarter |
|---|---|---|---|
| Lead (PB90) | 0 mg/L | 2025-01-01 – 2025-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2024-01-01 – 2024-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2023-01-01 – 2023-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2022-01-01 – 2022-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2021-01-01 – 2021-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2020-01-01 – 2020-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2019-01-01 – 2019-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2017-01-01 – 2017-12-31 | 2026Q3 |
| Substance | Published result | Sample date | Location / source |
|---|---|---|---|
| COLOR | < 5.000000000 UNITS | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| NITRITE | < 0.050000000 MG/L | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| CALCIUM | 19 MG/L | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| SILICA | 5.3 MG/L | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| ORTHOPHOSPHATE | 0.64 MG/L | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| HYDROXIDE AS CALCIUM CARBONATE | < 3.000000000 MG/L | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| ODOR | < 1.000000000 TON | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| ALKALINITY, BICARBONATE | 52 MG/L | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| TURBIDITY | < 0.300000000 NTU | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| ALKALINITY, CARBONATE | < 3.000000000 MG/L | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| NITROGEN-AMMONIA AS (N) | < 0.100000000 MG/L | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
| CONDUCTIVITY @ 25 C UMHOS/CM | 330 UMHO/CM | 2026-07-08 | SURFACE WATER TREATMENT PLANT EFFLUENT / California DDW laboratory results |
State sampling points can include untreated water. Publisher qualifiers and units are retained; consult the full source notes before interpreting a record.
Download state records with source notes (CSV)
Published compliance history
2 imported records. Status is as recorded in the source; historical records are not current advisories. Missing records do not establish that no violations occurred.
| Rule / record | Period | Recorded status | Health-based (EPA classification) | Source quarter |
|---|---|---|---|---|
| Lead and Copper Rule / Follow-up Or Routine LCR Tap M/R | 2018-01-01 – — | Resolved | No | 2026Q3 |
| Stage 2 Disinfectants and Disinfection Byproducts Rule / Maximum Contaminant Level Violation, Average | 2017-01-01 – 2017-03-31 | Resolved | Yes | 2026Q3 |
Source dates and refresh checks
A refresh check is not a sample date. Publication periods, sample dates and checks are shown separately.
- EPA SDWIS lead/copper summaries and service areas — source period: — – —; last checked: 2026-10-17
- EPA SDWIS contacts and compliance records — source period: — – —; last checked: 2026-10-17
- EPA UCMR 5 sample results — source period: 2023-01-03 – 2026-06-17; last checked: 2026-10-17
- California DDW laboratory results — last successful check: 2026-10-17
Administrative contact (EPA filing)
Kovich, Mark: 408-828-7007
An administrative filing contact may not be a customer-service line. Confirm current contact details with the provider.