Drinking water quality · 2024
· Verified
What's in Hayward, CA tap water
29 contaminants were measured in the Hayward, 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
- 29
- Over federal limit
- 2
- Approaching the limit
- 2
- Worst contaminant
- Bromate
- Service area
- CA
PFAS — EPA UCMR5 (2023–2025)
1 PFAS compound detected in Hayward, 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)below national p90 (18 ng/L across detecting U.S. systems)
Where your water comes from · EPA SDWIS
Hayward, CA's drinking water comes from surface water, drawn from 9 sources.
Source
- BRIONES RESERVOIR
- LAFAYETTE WTP INTAKE
- ORINDA WTP INTAKE
- PARDEE RESERVOIR
- + 5 more
Treatment
- LAFAYETTE WTP
- ORINDA WTP
- SOBRANTE WTP
- + 3 more
Distribution
Also buys water from CONTRA COSTA WATER DISTRICT.
Historical readings · EPA Six-Year Review (2012–2019)
2 contaminants historically over EPA limits in Hayward, 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) |
|---|---|---|---|
NITRATE NITRITE worst: 2013 | 400 mg/L 40.0× | 10 mg/L | '13'17 |
GROSS BETA worst: 2017 | 4 mrem/yr 1.0× | 4 mrem/yr | '12'13'14'15'16'17'19 |
ARSENIC worst: 2012 | 0.0046 mg/L within below national p90 | 0.01 mg/L | '12'13 |
FLUORIDE worst: 2013 | 1 mg/L within | 4 mg/L | '12'13'14'15'16'17'18'19 |
ASBESTOS worst: 2013 | 1.2 MFL within below national p90 | 7 MFL | '13'15'17'18'19 |
CHROMIUM worst: 2013 | 0.012 mg/L within above national p90 | 0.1 mg/L | '13 |
NITRATE worst: 2015 | 0.549 mg/L within | 10 mg/L | '15'17 |
URANIUM worst: 2017 | 0.00149 ug/L within below national p90 | 30 ug/L | '12'14'15'16'17 |
LEAD worst: 2017 | 0.0066 mg/L | — | '17 |
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| BromateA disinfection byproduct formed when bromide-containing water is treated with ozone. | 0–1.7 ug/LReported levelSobrante | 0.1 ug/LPublic health goal | At or above the limit |
| HAA5Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter. | 50 ug/LAverageSystem-wide | 60 ug/LMCL | Approaching the limit |
+By source (2)— Walnut Creek, USL
| |||
| TTHMTotal trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. | 57 ug/LAverageSystem-wide | 80 ug/LMCL | Within the limit |
+By source (2)— Walnut Creek, USL
| |||
| NDMA | 3.9 ng/LAverageEBMUD Results System | 10 ng/LNL | Within the limit |
+By source (3)— USL, EBMUD Results System, Walnut Creek
| |||
| ChlorateA byproduct that can form during disinfection, especially when hypochlorite solutions degrade. | 108 ug/LAverageEBMUD Results System | 800 ug/LNL | Within the limit |
+By source (3)— USL, EBMUD Results System, Walnut Creek
| |||
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 0.3 ug/LAverageEBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 0.2 ug/LPublic health goal | At or above the limit |
+By source (2)— Walnut Creek, USL
| |||
| AluminumA common element sometimes used as a treatment coagulant. | 0–56 ug/LAverageEBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 600 ug/LPublic health goal | Within the limit |
+By source (2)— USL, Walnut Creek
| |||
| BoronA naturally occurring element from rock and soil. | Not detected ug/LAverageEBMUD Results System | 1 ug/LNL | Within the limit |
+By source (3)— USL, Walnut Creek, EBMUD Results System
| |||
| CalciumA naturally occurring mineral that contributes to water hardness. | 33–34 mg/LReported levelUSL | None set | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
| MagnesiumA naturally occurring mineral that contributes to water hardness. | 13–14 mg/LReported levelUSL | None set | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
| PotassiumA naturally occurring mineral from rock and soil. | 2 mg/LReported levelUSL | None set | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
| SilicaA naturally occurring compound from sand and rock. | 10–12 mg/LReported levelSobrante | None set | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
| SodiumA naturally occurring salt component. | 32–35 mg/LReported levelUSL | None set | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
Disinfectants
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChloramineA longer-lasting disinfectant made by combining chlorine with ammonia. | 2.4 mg/LAverageSystem-wide | 4 mg/LPublic health goal | Within the limit |
+By source (2)— Walnut Creek, USL
| |||
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Specific ConductanceA measure of how well water conducts electricity, which tracks dissolved mineral content. | 127AverageSystem-wide | 900MCL | Within the limit |
+By source (2)— USL, Walnut Creek
| |||
| Total Dissolved SolidsTotal dissolved solids — the combined content of all dissolved minerals and salts. | 65 mg/LAverageSystem-wide | 500 mg/LMCL | Within the limit |
+By source (2)— USL, Walnut Creek
| |||
| TurbidityA measure of cloudiness from suspended particles in the water. | 0.02 NTUAverageEBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 1 NTUMCL | Within the limit |
+By source (2)— USL, Walnut Creek
| |||
| AlkalinityA measure of the water's capacity to neutralize acids. | 130–140 mg/LReported levelUSL | None set | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
| HardnessA measure of dissolved calcium and magnesium minerals. | 140–160 mg/LReported levelUSL | None set | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
| pHA measure of how acidic or basic the water is. | 9.1–9.4Reported levelOrinda | None set | Detected — no federal limit |
+By source (2)— Walnut Creek, USL
| |||
| TOCTotal organic carbon — a measure of organic material dissolved in the water. | 5.1–6.6 mg/LReported levelUSL | None set | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| SulfateA naturally occurring mineral from rock and soil. | 7 mg/LAverageSystem-wide | 250 mg/LMCL | Within the limit |
+By source (2)— USL, Walnut Creek
| |||
| ChlorideA naturally occurring salt compound. | 6 mg/LAverageSystem-wide | 250 mg/LMCL | Within the limit |
+By source (2)— USL, Walnut Creek
| |||
PFAS ("forever chemicals")
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Perfluorohexanoic acidPerfluorohexanoic acid, a shorter-chain PFAS 'forever chemical.' | Not detected ng/LAverageEBMUD Results System | 1 ng/LNL | Within the limit |
+By source (3)— USL, EBMUD Results System, Walnut Creek
| |||
Microbial
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Total ColiformA group of bacteria used as an indicator of overall water-system sanitation. | 0.3AverageEBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 0Public health goal | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Gross AlphaGross alpha particle activity — a combined measure of alpha-emitting radioactive substances. | 3.1 pCi/LAverageEBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 0 pCi/LPublic health goal | Detected — no federal limit |
+By source (2)— USL, Walnut Creek
| |||
People also ask about Hayward, CA's water
+Is Hayward, CA tap water safe to drink in 2024?
The 2024 Consumer Confidence Report for the Hayward, CA water utility lists 2 contaminants at or above the federal limit: Bromate and Chromium, Hexavalent. 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 Hayward, CA tap water?
29 contaminants were measured in Hayward, CA's 2024 Consumer Confidence Report, spanning metals, physical & aggregate, and disinfection byproducts. 19 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 Hayward, CA tap water?
2 contaminants in Hayward, CA's 2024 report sit at or above the federal limit: Bromate (17.0× the limit); Chromium, Hexavalent (1.5× 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 Hayward, CA tap water?
The contaminant with the highest measured value relative to its federal limit in the 2024 report is Bromate, at 17.0× the federal threshold. It belongs to the disinfection byproducts family of contaminants.
+Are any contaminants in Hayward, CA tap water approaching the federal limit?
2 contaminants are between 80% and 100% of the federal limit in this report: HAA5 and 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 Hayward, 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 Hayward, 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.