Drinking water quality · 2023
· Verified
· PWSID CA5010039
What's in Western Hills Water District/diablo Gran — Patterson, Ca, CA tap water
Only 7 of 27 core regulated contaminants were reported for Western Hills Water District/diablo Gran — Patterson, Ca, CA. What was measured is not clean — but most of the picture is missing.
- !1 contaminant at or above a federal limit — worst is Nitrate at 1.3x
- !1 contaminant within 20% of a limit
- !7 of 27 core regulated contaminants reported — 20 never appear in this report
- ✓No open federal violations
+How this score is calculated
Every system starts at 100. Points come off for measured levels, for the federal violation record, and for how much of the core regulated set the utility actually reported. All three inputs are the utility's own published numbers and EPA's own records.
- −17 contaminants at or above a federal limit
- −4 contaminants within 20% of a limit
- −0 open health-based violations
- −0 open monitoring / reporting violations
- −0 health-based violations resolved in the last 5 years
- −19 core regulated contaminants never reported (7/27)
A 90–100 · B 80–89 · C 70–79 · D 60–69 · F below 60. A system reporting under a third of the core set is capped at C however clean its numbers look — a short report is not a clean bill of health.
Full grading methodology, constant for constant →What to worry about
- Nitrate1.3× the federal limit0–13 mg/L · limit 10 mg/L
Levels above the federal limit can cause 'blue baby syndrome,' a serious oxygen-transport condition in infants.
Higher than 95% of CA systems that report it · higher than 95% of U.S. systems
- TTHM84% of the federal limit9.1–67 ug/L · limit 80 ug/L
Long-term exposure above the federal limit is linked to liver, kidney, and central-nervous-system effects and increased cancer risk.
Higher than 90% of CA systems that report it · higher than 85% of U.S. systems
+7 contaminants were measured and came in below the limitShow all
| Contaminant | Measured | Federal limit |
|---|---|---|
| HAA5 | 0–32 ug/L | 60 ug/L |
| Copper | 0.085 mg/L | 1.3 mg/L |
| Arsenic | Not detected ug/L | 10 ug/L |
| Lead | 0.0 mg/L | 0.015 mg/L |
| Manganese | Not detected mg/L | 500 mg/L |
| Escherichia coli (E. coli) | 0 | 0 |
| TOC | 1.2–2.8 | — |
What this report doesn't tell you
20 of the 27 contaminants a community water system normally reports do not appear anywhere in Western Hills Water District/diablo Gran — Patterson, Ca, CA's data. Absent is not the same as absent-from-the-water — it means nobody published a number.
+Full detail: PFAS testing, water source, historical monitoring, and the federal violation record
Compliance history
Federal Safe Drinking Water Act violation & enforcement records (EPA SDWIS). A violation is a regulatory determination by the state or EPA — separate from the measured levels above.
- Maximum contaminant level exceededHealth-based31 violations on record · most recent Dec 2016resolved
- Treatment technique violationHealth-based1 violation on record · most recent Apr 2006resolved
- Monitoring1 violation on recordresolved
Source: EPA SDWIS / ECHO. View the full federal record on EPA ECHO ↗