# Cws - Selma — San Jose, Ca, CA — Drinking Water Quality (2023)

> Contaminant levels for the Cws - Selma — San Jose, Ca, CA public water system from its 2023 Consumer Confidence Report, compared to federal limits.

- Page: https://www.thewatermap.com/water/ca/cws-selma-san-jose-ca/2023
- JSON API: https://www.thewatermap.com/api/water/ca/cws-selma-san-jose-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: 21
- Contaminants with a federal limit: 7
- 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 | 1.1 mg/L (Average) | Distribution System-Wide | 4 mg/L (MCL) | Within the limit |
| HAA5 | Disinfection byproducts | Not detected ug/L (Average) | Distribution System-Wide Highest Annual | No federal limit | None detected |
| TTHM | Disinfection byproducts | Not detected ug/L (Average) | Distribution System-Wide Highest Annual | No federal limit | None detected |
| Fluoride | Inorganic chemicals | Not detected mg/L (Average) | System-wide | 4 mg/L (MCL) | Within the limit |
| Nitrate | Inorganic chemicals | 2.6 mg/L (Average) | System-wide | 10 mg/L (MCL) | Within the limit |
| Arsenic | Metals | Not detected ug/L (Average) | System-wide | No federal limit | Within the limit |
| Calcium | Metals | 19 mg/L (Average) | Groundwater | No federal limit | Detected — no federal limit |
| Chromium, Hexavalent | Metals | 1.6 ug/L (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 | Not detected ug/L (90th percentile) | At the tap | No federal limit | None detected |
| Magnesium | Metals | 0.97 mg/L (Average) | Groundwater | No federal limit | Detected — no federal limit |
| Potassium | Metals | 0.89 mg/L (Average) | Groundwater | No federal limit | Detected — no federal limit |
| Sodium | Metals | 22 mg/L (Average) | Groundwater | No federal limit | Detected — no federal limit |
| Vanadium | Metals | 8.2 ug/L (Average) | Groundwater | 50 ug/L (NL) | Detected — no federal limit |
| Total Coliform | Microbial | 0 (Maximum) | Monthly | No federal limit | None detected |
| Alkalinity | Physical & aggregate | 66 mg/L (Average) | Groundwater | No federal limit | Detected — no federal limit |
| Hardness | Physical & aggregate | 51 mg/L (Average) | Groundwater | No federal limit | Detected — no federal limit |
| pH | Physical & aggregate | 8.3 (Average) | Groundwater | No federal limit | Detected — no federal limit |
| Gross Alpha | Radionuclides | Not detected pCi/L (Average) | System-wide | 15 pCi/L (MCL) | Within the limit |
| Uranium | Radionuclides | 2.7 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 |

## 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.
- **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.
- **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.
- **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.
- **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.
- **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.
- **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.
- **Gross Alpha** — Gross alpha particle activity — a combined measure of alpha-emitting radioactive substances. Long-term exposure above the federal limit 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.

## 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._