# City of Grass Valley — Grass Valley, Ca, CA — Drinking Water Quality (2023)

> Contaminant levels for the City of Grass Valley — Grass Valley, Ca, CA public water system from its 2023 Consumer Confidence Report, compared to federal limits.

- Page: https://www.thewatermap.com/water/ca/grass-valley-grass-valley-ca/2023
- JSON API: https://www.thewatermap.com/api/water/ca/grass-valley-grass-valley-ca/2023
- 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: 2023
- Contaminants measured: 13
- Contaminants with a federal limit: 3
- Contaminants at or above the federal limit: 0
- Part of The Water Map — https://www.thewatermap.com

## Contaminants measured

| Contaminant | Category | Measured level | Sampling context | Federal limit | Status |
|---|---|---|---|---|---|
| Chlorine | Disinfectants | 0.57–0.93 mg/L (Range) | System-wide | 4 mg/L (MCL) | Within the limit |
| Chloroform | Disinfection byproducts | 16–35 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| HAA5 | Disinfection byproducts | 6.3–22.6 ug/L (Range) | System-wide | No federal limit | Within the limit |
| TTHM | Disinfection byproducts | 17–37 ug/L (Range) | System-wide | No federal limit | Within the limit |
| Chloride | Inorganic chemicals | 2.38 mg/L (Reported level) | System-wide | No federal limit | Detected — no federal limit |
| Sulfate | Inorganic chemicals | 0.93 mg/L (Reported level) | System-wide | No federal limit | Detected — no federal limit |
| Copper | Metals | 0.736 mg/L (90th percentile) | At the tap | 1.3 mg/L (Action level) | Within the limit |
| Lead | Metals | 0.17 ug/L (90th percentile) | At the tap | No federal limit | Within the limit |
| Escherichia coli (E. coli) | Microbial | 0 (Highest single sample) | No. of Detections | No federal limit | None detected |
| Specific Conductance | Physical & aggregate | 40.1 (Reported level) | System-wide | No federal limit | Detected — no federal limit |
| TOC | Physical & aggregate | 0–1.1 mg/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Total Dissolved Solids | Physical & aggregate | 36 mg/L (Reported level) | System-wide | No federal limit | Detected — no federal limit |
| Gross Alpha | Radionuclides | 1.26 (Reported level) | System-wide | 15 (MCL) | Detected — no federal limit |

## What these contaminants are

- **Chlorine** — A disinfectant added to drinking water to kill bacteria and viruses. Effective and necessary, but high residual levels can cause taste and odor issues; the EPA caps the residual disinfectant level.
- **Chloroform** — A trihalomethane formed when chlorine reacts with organic matter in water. A component of regulated total trihalomethanes; long-term exposure is linked to liver and kidney effects.
- **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.
- **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.
- **Copper** — A metal that enters water from corroding household plumbing. Short-term exposure causes stomach distress; long-term exposure can damage the liver and kidneys.
- **Lead** — A toxic metal that leaches into water from old service lines, solder, and plumbing fixtures. There is no safe level of lead; it harms brain development in children and raises blood pressure in adults. The EPA sets an action level, not a health goal above zero.
- **Escherichia coli (E. coli)** — Escherichia coli — bacteria found in the gut of humans and animals. Its presence in drinking water indicates fecal contamination and a real risk of waterborne illness.
- **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.
- **Gross Alpha** — Gross alpha particle activity — a combined measure of alpha-emitting radioactive substances. Long-term exposure above the federal limit 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 2026-06-04 from thewatermap.com._