# Three Valleys MWD — Claremont, Ca, CA — Drinking Water Quality (2023)

> Contaminant levels for the Three Valleys MWD — Claremont, Ca, CA public water system from its 2023 Consumer Confidence Report, compared to federal limits.

- Page: https://www.thewatermap.com/water/ca/three-valleys-mwd-claremont-ca/2023
- JSON API: https://www.thewatermap.com/api/water/ca/three-valleys-mwd-claremont-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: 61
- Contaminants with a federal limit: 5
- 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 |
|---|---|---|---|---|---|
| Bromate | Disinfection byproducts | 2 ug/L (Reported level) | Column 3 | No federal limit | Within the limit |
| HAA5 | Disinfection byproducts | 0–23 ug/L (Reported level) | Column 3 | No federal limit | Within the limit |
| Perchlorate | Disinfection byproducts | Not detected ug/L (Reported level) | Column 5 | No federal limit | None detected |
| TTHM | Disinfection byproducts | 12–45 ug/L (Reported level) | Column 3 | No federal limit | Within the limit |
| Chloride | Inorganic chemicals | 96–106 mg/L (Reported level) | Column 3 | No federal limit | Detected — no federal limit |
| Sulfate | Inorganic chemicals | 200–225 mg/L (Reported level) | Column 3 | No federal limit | Detected — no federal limit |
| Aluminum | Metals | 0–150 ug/L (Reported level) | Column 3 | No federal limit | Detected — no federal limit |
| Copper | Metals | Not detected mg/L (Reported level) | Column 7 | No federal limit | None detected |
| Iron | Metals | Not detected ug/L (Reported level) | Column 5 | No federal limit | None detected |
| Manganese | Metals | Not detected ug/L (Reported level) | Column 5 | No federal limit | None detected |
| Selenium | Metals | Not detected ug/L (Reported level) | Column 7 | No federal limit | None detected |
| Strontium | Metals | Not detected pCi/L (Reported level) | Column 3 | No federal limit | None detected |
| Thallium | Metals | Not detected ug/L (Reported level) | Column 7 | No federal limit | None detected |
| Cryptosporidium | Microbial | Not detected (Reported level) | Miramar Groundwater Grand Well | No federal limit | None detected |
| Escherichia coli (E. coli) | Microbial | 0 (Reported level) | Miramar Groundwater Well #2 | No federal limit | None detected |
| Giardia lamblia | Microbial | Not detected (Reported level) | Miramar Groundwater Miragrand Well | No federal limit | None detected |
| Total Coliform | Microbial | 0–0.1 % (Reported level) | Weymouth Effluent | No federal limit | Detected — no federal limit |
| Alachlor | Other | Not detected ug/L (Reported level) | Miramar Groundwater Grand Well | No federal limit | None detected |
| Carbofuran | Other | Not detected ug/L (Reported level) | Miramar Groundwater Well #2 | No federal limit | None detected |
| Chlordane | Other | Not detected ng/L (Reported level) | Weymouth Effluent | No federal limit | None detected |
| Deha | Other | Not detected ug/L (Reported level) | Weymouth Effluent | No federal limit | None detected |
| Dehp | Other | Not detected ug/L (Reported level) | Miramar Groundwater Grand Well | No federal limit | None detected |
| Dichloroethane 12 | Other | Not detected ug/L (Reported level) | Column 6 | No federal limit | None detected |
| Dichloropropane 12 | Other | Not detected ug/L (Reported level) | Column 6 | No federal limit | None detected |
| Dinoseb | Other | Not detected ug/L (Reported level) | Miramar Groundwater Well #2 | No federal limit | None detected |
| Diquat | Other | Not detected ug/L (Reported level) | Column 7 | No federal limit | None detected |
| Endothall | Other | Not detected ug/L (Reported level) | Column 6 | No federal limit | None detected |
| Endrin | Other | Not detected ug/L (Reported level) | Column 5 | No federal limit | None detected |
| Glyphosate | Other | Not detected ug/L (Reported level) | Column 5 | No federal limit | None detected |
| Heptachlor | Other | Not detected ng/L (Reported level) | Column 5 | No federal limit | None detected |
| Heptachlor Epoxide | Other | Not detected ng/L (Reported level) | Column 3 | No federal limit | None detected |
| Hexachlorobenzene | Other | Not detected ug/L (Reported level) | Column 4 | No federal limit | None detected |
| Hexachlorocyclopentadiene | Other | Not detected ug/L (Reported level) | Column 6 | No federal limit | None detected |
| Lindane | Other | Not detected ng/L (Reported level) | Column 6 | No federal limit | None detected |
| Methoxychlor | Other | Not detected ug/L (Reported level) | Column 7 | No federal limit | None detected |
| Oxamyl | Other | Not detected ug/L (Reported level) | Column 3 | No federal limit | None detected |
| Pcb Total | Other | Not detected ng/L (Reported level) | Column 5 | No federal limit | None detected |
| Pentachlorophenol | Other | Not detected ug/L (Reported level) | Column 4 | No federal limit | None detected |
| Picloram | Other | Not detected ug/L (Reported level) | Column 7 | No federal limit | None detected |
| Toxaphene | Other | Not detected ug/L (Reported level) | Column 5 | No federal limit | None detected |
| Trichlorobenzene 124 | Other | Not detected ug/L (Reported level) | Column 5 | No federal limit | None detected |
| Twofourd | Other | Not detected ug/L (Reported level) | Miramar Groundwater Well #2 | No federal limit | None detected |
| Color | Physical & aggregate | 1 (Reported level) | Column 3 | No federal limit | Detected — no federal limit |
| Odor | Physical & aggregate | 1 (Reported level) | Column 6 | No federal limit | Detected — no federal limit |
| Specific Conductance | Physical & aggregate | 912–996 (Reported level) | Column 3 | No federal limit | Detected — no federal limit |
| TOC | Physical & aggregate | 2.4 mg/L (Reported level) | Column 3 | No federal limit | Detected — no federal limit |
| Total Dissolved Solids | Physical & aggregate | 506–587 mg/L (Reported level) | Metropolitan Water District | No federal limit | Detected — no federal limit |
| Turbidity | Physical & aggregate | 0.34 NTU (Reported level) | Miramar Groundwater Well #1 | No federal limit | Within the limit |
| Combined Radium | Radionuclides | 0.82 pCi/L (Reported level) | Column 8 | 0.05 pCi/L (Public health goal) | Within the limit |
| Gross Alpha | Radionuclides | Not detected pCi/L (Reported level) | Column 3 | 15 pCi/L (MCL) | None detected |
| Gross Beta Particle Activity | Radionuclides | 0–5 pCi/L (Reported level) | Column 3 | No federal limit | Detected — no federal limit |
| Radon | Radionuclides | Not detected pCi/L (Reported level) | Metropolitan Water District | No federal limit | None detected |
| Uranium | Radionuclides | 3.4 pCi/L (Reported level) | Column 8 | 20 pCi/L (MCL) | Detected — no federal limit |
| 1,2,3-TCP | VOCs & pesticides | Not detected ng/L (Reported level) | Miramar Groundwater Grand Well | No federal limit | None detected |
| Atrazine | VOCs & pesticides | Not detected ug/L (Reported level) | Miramar Groundwater Miragrand Well | No federal limit | None detected |
| Benzo(a)pyrene | VOCs & pesticides | Not detected ng/L (Reported level) | Miramar Effluent | No federal limit | None detected |
| Dalapon | VOCs & pesticides | Not detected ug/L (Reported level) | Miramar Groundwater Well #1 | 200 ug/L (MCL) | None detected |
| DBCP | VOCs & pesticides | Not detected ng/L (Reported level) | Miramar Groundwater Grand Well | No federal limit | None detected |
| Ethylene dibromide | VOCs & pesticides | Not detected ng/L (Reported level) | Column 5 | 5000000 ng/L (MCL) | None detected |
| MTBE | VOCs & pesticides | Not detected ug/L (Reported level) | Column 4 | No federal limit | None detected |
| Simazine | VOCs & pesticides | Not detected ug/L (Reported level) | Column 8 | No federal limit | None detected |

## What these contaminants are

- **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.
- **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.
- **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.
- **Aluminum** — A common element sometimes used as a treatment coagulant. Regulated only as a secondary (cosmetic) standard; high levels can discolor water.
- **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.
- **Iron** — A naturally occurring metal common in groundwater. Regulated only as a secondary (cosmetic) standard; causes rusty color, staining, and metallic taste.
- **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.
- **Selenium** — A trace element from natural deposits and industrial discharge. Essential in tiny amounts, but long-term exposure above the federal limit can cause hair and fingernail loss and circulatory problems.
- **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.
- **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.
- **Color** — A measure of visible tint in the water. Regulated only as a secondary (cosmetic) standard.
- **Odor** — A measure of detectable smell in the water. Regulated only as a secondary (cosmetic) standard.
- **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.
- **Combined Radium** — Combined radium-226 and radium-228 — naturally occurring radioactive elements. Long-term exposure above the federal limit increases the risk of bone cancer.
- **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.
- **Radon** — A naturally occurring radioactive gas that can dissolve into groundwater. No enforceable federal limit in drinking water yet; inhalation of released radon raises lung-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.
- **Atrazine** — A widely used agricultural herbicide that reaches water through runoff. Long-term exposure above the federal limit can affect the cardiovascular and reproductive systems.
- **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.

## 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._