# Gswc - Claremont — San Dimas, Ca, CA — Drinking Water Quality (2020)

> Contaminant levels for the Gswc - Claremont — San Dimas, Ca, CA public water system from its 2020 Consumer Confidence Report, compared to federal limits.

- Page: https://www.thewatermap.com/water/ca/gswc-claremont-san-dimas-ca/2020
- JSON API: https://www.thewatermap.com/api/water/ca/gswc-claremont-san-dimas-ca/2020
- 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: 2020
- Contaminants measured: 16
- Contaminants with a federal limit: 7
- Contaminants at or above the federal limit: 1
- Part of The Water Map — https://www.thewatermap.com

## Contaminants measured

| Contaminant | Category | Measured level | Sampling context | Federal limit | Status |
|---|---|---|---|---|---|
| Chlorine | Disinfectants | 1.5 mg/L (Average) | System-wide | 4 mg/L (MCL) | Within the limit |
| HAA5 | Disinfection byproducts | 37 (Average) | System-wide | No federal limit | Detected — no federal limit |
| Perchlorate | Disinfection byproducts | Not detected (Average) | System-wide | No federal limit | Detected — no federal limit |
| TTHM | Disinfection byproducts | 39 ug/L (Average) | System-wide | No federal limit | Within the limit |
| Fluoride | Inorganic chemicals | 0.31 mg/L (Average) | System-wide | 4 mg/L (MCL) | Within the limit |
| Nitrate | Inorganic chemicals | 4.2 mg/L (Average) | System-wide | 10 mg/L (MCL) | Within the limit |
| Arsenic | Metals | Not detected (Average) | System-wide | No federal limit | Detected — no federal limit |
| Copper | Metals | Not detected mg/L (90th percentile) | At the tap | 1.3 mg/L (Action level) | None detected |
| Lead | Metals | 0.23 ug/L (90th percentile) | At the tap | No federal limit | Within the limit |
| Manganese | Metals | 1.8 (Average) | System-wide | No federal limit | Detected — no federal limit |
| Perfluorohexanoic acid | PFAS ("forever chemicals") | 5.8 ng/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| PFOA | PFAS ("forever chemicals") | 4.7 ng/L (Average) | System-wide | 5.1 ng/L (NL) | At or above the limit |
| Gross Beta Particle Activity | Radionuclides | Not detected pCi/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Uranium | Radionuclides | 1.6 pCi/L (Average) | System-wide | 20 pCi/L (MCL) | Detected — no federal limit |
| DBCP | VOCs & pesticides | Not detected ng/L (Average) | System-wide | No federal limit | Within the limit |
| Trichloroethylene | VOCs & pesticides | Not detected (Average) | System-wide | 5 (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.
- **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.
- **Perchlorate** — A chemical used in rocket fuel and fireworks that can also form during disinfection. Can interfere with thyroid hormone production; has no national enforceable limit but is regulated in some states.
- **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.
- **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.
- **Nitrate** — A compound from fertilizer runoff, septic systems, and erosion of natural deposits. Levels above the federal limit can cause 'blue baby syndrome,' a serious oxygen-transport condition in infants.
- **Arsenic** — A naturally occurring element that also enters water from industry and agriculture. A known human carcinogen; long-term exposure is linked to skin, bladder, and lung cancer.
- **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.
- **Manganese** — A naturally occurring metal from soil and rock. No enforceable federal limit; high levels stain fixtures and laundry and can affect taste, with a health advisory for infants.
- **Perfluorohexanoic acid** — Perfluorohexanoic acid, a shorter-chain PFAS 'forever chemical.' Monitored under EPA rules; persistent and widely detected.
- **PFOA** — Perfluorooctanoic acid, a PFAS 'forever chemical' once used in nonstick and stain-resistant products. Linked to cancer, liver damage, and immune effects; the EPA set an enforceable limit of 4 parts per trillion.
- **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.
- **Uranium** — A naturally occurring radioactive metal from erosion of natural deposits. Long-term exposure above the federal limit can damage the kidneys and increase cancer risk.
- **DBCP** — 1,2-dibromo-3-chloropropane — a banned soil fumigant pesticide. A probable human carcinogen; long-term exposure above the federal limit can cause reproductive harm.
- **Trichloroethylene** — An industrial solvent (TCE) used in metal degreasing. A known human carcinogen; long-term exposure above the federal limit can damage the liver.

## 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._