Drinking water quality · 2024
· Verified
What's in Diablo Water District, CA tap water
15 contaminants were measured in the Diablo Water District, CA water system's 2024 annual report. Each is shown below against its federal limit — 2 sit at or above that limit.
- Reporting year
- 2024
- Contaminants measured
- 15
- Over federal limit
- 2
- Approaching the limit
- 1
- Worst contaminant
- Chromium, Hexavalent
- Service area
- CA
PFAS — EPA UCMR5 (2023–2025)
2 PFAS compounds detected in Diablo Water District, CA
The EPA finalized the first-ever federal drinking-water limits for six PFAS compounds in April 2024. These numbers come straight from EPA's UCMR5 lab dataset — every U.S. system serving more than 3,300 people tested every PFAS sample at an entry point to its distribution system. PFAS not listed below were either tested and not detected, or not yet sampled.
PFBA
● Detected (no federal limit)near national p90 (18 ng/L across detecting U.S. systems)
Lithium
● Detected (no federal limit)near national p90 (76.59999999999991 mg/L across detecting U.S. systems)
Where your water comes from · EPA SDWIS
Diablo Water District, CA buys its drinking water from ESCONDIDO, CITY OF, SAN DIEGO COUNTY WATER AUTHORITY.
Source
Treatment
Distribution
Also buys water from ESCONDIDO, CITY OF, SAN DIEGO COUNTY WATER AUTHORITY.
Historical readings · EPA Six-Year Review (2012–2019)
11 historically-detected contaminants in Diablo Water District, CA
Every U.S. public water system reports compliance-monitoring data to EPA. The Six-Year Review releases the 2012–2019 window as a single dataset — here's what your system reported, year by year. Values shown are the highest detection per analyte per year, compared to the federal MCL.
| Contaminant | Worst detection | EPA limit | Years (2012–2019) |
|---|---|---|---|
TTHM worst: 2014 | 0.046 mg/L within | 0.08 mg/L | '12'13'14'15'16'17'18'19 |
HAA5 worst: 2015 | 0.03 mg/L within | 0.06 mg/L | '12'13'14'15'16'17'18'19 |
DBAA worst: 2012 | 0.0033 mg/L | — | '12'13'14'15'16'17'18'19 |
DCAA worst: 2012 | 0.0032 mg/L | — | '12'13'14'15'16'17'18'19 |
MBAA worst: 2014 | 0.0031 mg/L | — | '14'15 |
MCAA worst: 2013 | 0.0046 mg/L | — | '13'14'15'16'17'19 |
TCAA worst: 2012 | 0.0016 mg/L | — | '12'13'14'15'16'17'18'19 |
BROMODICHLOROMETHANE worst: 2012 | 0.0049 mg/L | — | '12'13'14'15'16'17'18'19 |
BROMOFORM worst: 2012 | 0.0065 mg/L | — | '12'13'14'15'16'17'18'19 |
CHLOROFORM worst: 2012 | 0.0029 mg/L | — | '12'13'14'15'16'17'18'19 |
DIBROMOCHLOROMETHANE worst: 2012 | 0.0084 mg/L | — | '12'13'14'15'16'17'18'19 |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 0.11 ug/LAverageSystem-wide | 0.02 ug/LMCLG | At or above the limit |
| CopperA metal that enters water from corroding household plumbing. | 0.15 mg/L90th percentileAt the tap | 0.3 mg/LMCLG | Within the limit |
| AluminumA common element sometimes used as a treatment coagulant. | 0.06 mg/LAverageSystem-wide | 0.6 mg/LMCLG | Within the limit |
| LeadA toxic metal that leaches into water from old service lines, solder, and plumbing fixtures. | Not detected ug/L90th percentileAt the tap | 0.2 ug/LMCLG | None detected |
Disinfection byproducts
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| FluorideA mineral often added to drinking water to help prevent tooth decay. | 0.8 mg/LAverageSystem-wide | 1 mg/LMCLG | Approaching the limit |
| NitrateA compound from fertilizer runoff, septic systems, and erosion of natural deposits. | 1.2 mg/LAverageSystem-wide | 10 mg/LMCLG | Within the limit |
| Asbestos | Not detected MFLAverageSystem-wide | 7 MFLMCLG | Within the limit |
Disinfectants
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChloramineA longer-lasting disinfectant made by combining chlorine with ammonia. | 2.6 mg/LRunning annual avgHighest Quarterly | 4 mg/LMCLG | Within the limit |
Microbial
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Total ColiformA group of bacteria used as an indicator of overall water-system sanitation. | 0.5 %AverageSystem-wide | 5 %MCL | Within the limit |
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TurbidityA measure of cloudiness from suspended particles in the water. | 0.44 NTURangeSystem-wide | 95 NTUMCL | Within the limit |
People also ask about Diablo Water District, CA's water
+Is Diablo Water District, CA tap water safe to drink in 2024?
The 2024 Consumer Confidence Report for the Diablo Water District, CA water utility lists 2 contaminants at or above the federal limit: Chromium, Hexavalent and Chlorite. Whether that means the water is "unsafe" depends on which contaminant, how long the exposure, and individual health factors. The table on this page shows the measured value, the federal threshold, and the regulated statistic used for compliance.
+What contaminants are in Diablo Water District, CA tap water?
15 contaminants were measured in Diablo Water District, CA's 2024 Consumer Confidence Report, spanning metals, disinfection byproducts, and inorganic chemicals. 14 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Which contaminants exceed federal limits in Diablo Water District, CA tap water?
2 contaminants in Diablo Water District, CA's 2024 report sit at or above the federal limit: Chromium, Hexavalent (5.5× the limit); Chlorite (4.0× the limit). The EPA enforces these limits against the regulated reporting statistic — typically a running annual average or 90th percentile — not a one-off sample spike.
+What is the worst contaminant in Diablo Water District, CA tap water?
The contaminant with the highest measured value relative to its federal limit in the 2024 report is Chromium, Hexavalent, at 5.5× the federal threshold. It belongs to the metals family of contaminants.
+Are any contaminants in Diablo Water District, CA tap water approaching the federal limit?
One contaminant is between 80% and 100% of the federal limit in this report: Fluoride. Approaching means measured but not in violation — a margin that can close quickly if conditions change.
+Where does the data on this page come from?
Every value is transcribed from Diablo Water District, CA's 2024 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is Diablo Water District, CA's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2024 report; a new report will replace it once the utility publishes its next annual update.