# Hercules, CA — Drinking Water Quality (2024)

> Contaminant levels for the Hercules, CA public water system from its 2024 Consumer Confidence Report, compared to federal limits.

- Page: https://www.thewatermap.com/water/ca/hercules/2024
- JSON API: https://www.thewatermap.com/api/water/ca/hercules/2024
- Source: the utility's annual Consumer Confidence Report (CCR)
- Verification: transcribed by a model, cross-checked by a second model, approved before publishing
- Reporting year: 2024
- Contaminants measured: 29
- Contaminants with a federal limit: 19
- Contaminants at or above the federal limit: 2
- Part of The Water Map — https://www.thewatermap.com

## Contaminants measured

| Contaminant | Category | Measured level | Sampling context | Federal limit | Status |
|---|---|---|---|---|---|
| Chloramine | Disinfectants | 2.4 mg/L (Average) | System-wide | 4 mg/L (Public health goal) | Within the limit |
| Bromate | Disinfection byproducts | 0–1.7 ug/L (Reported level) | Sobrante | 0.1 ug/L (Public health goal) | At or above the limit |
| Chlorate | Disinfection byproducts | 108 ug/L (Average) | EBMUD Results System | 800 ug/L (NL) | Within the limit |
| HAA5 | Disinfection byproducts | 50 ug/L (Average) | System-wide | 60 ug/L (MCL) | Approaching the limit |
| NDMA | Disinfection byproducts | 3.9 ng/L (Average) | EBMUD Results System | 10 ng/L (NL) | Within the limit |
| TTHM | Disinfection byproducts | 57 ug/L (Average) | System-wide | 80 ug/L (MCL) | Within the limit |
| Chloride | Inorganic chemicals | 6 mg/L (Average) | System-wide | 250 mg/L (MCL) | Within the limit |
| Fluoride | Inorganic chemicals | 0.7–0.8 mg/L (Average) | EBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 1 mg/L (Public health goal) | Approaching the limit |
| Sulfate | Inorganic chemicals | 7 mg/L (Average) | System-wide | 250 mg/L (MCL) | Within the limit |
| Aluminum | Metals | 0–56 ug/L (Average) | EBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 600 ug/L (Public health goal) | Within the limit |
| Boron | Metals | Not detected ug/L (Average) | EBMUD Results System | 1 ug/L (NL) | Within the limit |
| Calcium | Metals | 33–34 mg/L (Reported level) | USL | No federal limit | Detected — no federal limit |
| Chromium, Hexavalent | Metals | 0.3 ug/L (Average) | EBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 0.2 ug/L (Public health goal) | At or above the limit |
| Magnesium | Metals | 13–14 mg/L (Reported level) | USL | No federal limit | Detected — no federal limit |
| Potassium | Metals | 2 mg/L (Reported level) | USL | No federal limit | Detected — no federal limit |
| Silica | Metals | 9–12 mg/L (Reported level) | USL | No federal limit | Detected — no federal limit |
| Sodium | Metals | 32–35 mg/L (Reported level) | USL | No federal limit | Detected — no federal limit |
| Total Coliform | Microbial | 0.3 (Average) | EBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 0 (Public health goal) | Detected — no federal limit |
| Perfluorohexanoic acid | PFAS ("forever chemicals") | Not detected ng/L (Average) | EBMUD Results System | 1 ng/L (NL) | Within the limit |
| PFBA | PFAS ("forever chemicals") | Not detected ng/L (Average) | EBMUD Results System | No federal limit | Detected — no federal limit |
| Alkalinity | Physical & aggregate | 130–140 mg/L (Reported level) | USL | No federal limit | Detected — no federal limit |
| Hardness | Physical & aggregate | 140–160 mg/L (Reported level) | USL | No federal limit | Detected — no federal limit |
| pH | Physical & aggregate | 9.1–9.4 (Reported level) | Orinda | No federal limit | Detected — no federal limit |
| Specific Conductance | Physical & aggregate | 127 (Average) | System-wide | 900 (MCL) | Within the limit |
| TOC | Physical & aggregate | 5.1–6.6 mg/L (Reported level) | USL | No federal limit | Detected — no federal limit |
| Total Dissolved Solids | Physical & aggregate | 65 mg/L (Average) | System-wide | 500 mg/L (MCL) | Within the limit |
| Turbidity | Physical & aggregate | 0.02 NTU (Average) | System-wide | 1 NTU (MCL) | Within the limit |
| Gross Alpha | Radionuclides | 3.1 pCi/L (Average) | EBMUD Results WATER TREATMENT PLANTS Individual Sample Results* Walnut Creek Lafayette Orinda Sobrante USL | 0 pCi/L (Public health goal) | Detected — no federal limit |
| Gross Beta Particle Activity | Radionuclides | 6.1 pCi/L (Average) | System-wide | 0 pCi/L (Public health goal) | Detected — no federal limit |

## What these contaminants are

- **Chloramine** — A longer-lasting disinfectant made by combining chlorine with ammonia. Holds disinfection further into the pipe network, but is regulated under the same residual-disinfectant cap as chlorine.
- **Bromate** — A disinfection byproduct formed when bromide-containing water is treated with ozone. Classified as a probable human carcinogen; the EPA sets a strict maximum contaminant level.
- **Chlorate** — A byproduct that can form during disinfection, especially when hypochlorite solutions degrade. Has no enforceable federal limit but is on the EPA contaminant candidate list; high levels can affect the thyroid.
- **HAA5** — Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter. Long-term exposure above the federal limit is associated with an increased cancer risk.
- **TTHM** — Total trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. Long-term exposure above the federal limit is linked to liver, kidney, and central-nervous-system effects and increased cancer risk.
- **Chloride** — A naturally occurring salt compound. Regulated only as a secondary (cosmetic) standard; high levels cause a salty taste and can corrode pipes.
- **Fluoride** — A mineral often added to drinking water to help prevent tooth decay. Beneficial at low levels, but long-term exposure above the federal limit can cause bone disease and tooth mottling.
- **Sulfate** — A naturally occurring mineral from rock and soil. No health-based federal limit; high levels can have a laxative effect and a bitter taste.
- **Aluminum** — A common element sometimes used as a treatment coagulant. Regulated only as a secondary (cosmetic) standard; high levels can discolor water.
- **Boron** — A naturally occurring element from rock and soil. No enforceable federal limit; the EPA has issued a health advisory level.
- **Calcium** — A naturally occurring mineral that contributes to water hardness. Not federally regulated for health; affects scaling and taste.
- **Chromium, Hexavalent** — Hexavalent chromium ('chromium-6') — the more toxic form of chromium. A known carcinogen by inhalation; regulated nationally only within the total-chromium limit, with stricter limits in some states.
- **Magnesium** — A naturally occurring mineral that contributes to water hardness. Not federally regulated for health; affects scaling and taste.
- **Potassium** — A naturally occurring mineral from rock and soil. Not federally regulated for health.
- **Silica** — A naturally occurring compound from sand and rock. Not federally regulated for health; relevant mainly for industrial water use.
- **Sodium** — A naturally occurring salt component. Not federally regulated for health; relevant for people on sodium-restricted diets.
- **Total Coliform** — A group of bacteria used as an indicator of overall water-system sanitation. Coliforms themselves are usually harmless, but their presence signals that disease-causing organisms could enter the system.
- **Perfluorohexanoic acid** — Perfluorohexanoic acid, a shorter-chain PFAS 'forever chemical.' Monitored under EPA rules; persistent and widely detected.
- **PFBA** — Perfluorobutanoic acid, a shorter-chain PFAS 'forever chemical.' Monitored under EPA rules; persistent in the environment and the human body.
- **Alkalinity** — A measure of the water's capacity to neutralize acids. Not federally regulated for health; relevant to corrosion control and treatment.
- **Hardness** — A measure of dissolved calcium and magnesium minerals. Not federally regulated for health; affects scaling, soap use, and taste.
- **pH** — A measure of how acidic or basic the water is. Regulated only as a secondary standard; very low or high pH can corrode pipes or affect taste.
- **Specific Conductance** — A measure of how well water conducts electricity, which tracks dissolved mineral content. Not federally regulated for health; used as a proxy for total dissolved solids.
- **TOC** — Total organic carbon — a measure of organic material dissolved in the water. Not harmful itself, but it is the raw material that forms disinfection byproducts; removal is a treatment requirement.
- **Total Dissolved Solids** — Total dissolved solids — the combined content of all dissolved minerals and salts. Regulated only as a secondary (cosmetic) standard; high levels affect taste and hardness.
- **Turbidity** — A measure of cloudiness from suspended particles in the water. High turbidity can shelter microbes from disinfection; the EPA enforces it through a treatment-technique standard.
- **Gross Alpha** — Gross alpha particle activity — a combined measure of alpha-emitting radioactive substances. Long-term exposure above the federal limit increases cancer risk.
- **Gross Beta Particle Activity** — Gross beta particle activity — a combined measure of beta-emitting radioactive substances. Long-term exposure above the federal screening level increases cancer risk.

## How to read this

- A water-quality report covers an entire service area, not a single address.
- 'Federal limit' is the EPA standard (MCL, action level, treatment technique, etc.) that the measured level is compared against.
- 'At or above the federal limit' means the utility's own reported figure met or exceeded that standard.

_Figures are the utility's own published numbers. Generated 2026-05-25 from thewatermap.com._