# Thornton, CO — Drinking Water Quality (2024)

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

- Page: https://www.thewatermap.com/water/co/thornton/2024
- JSON API: https://www.thewatermap.com/api/water/co/thornton/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: 19
- Contaminants with a federal limit: 12
- 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 |
|---|---|---|---|---|---|
| Chlorine | Disinfectants | 1.7–2.9 mg/L (Range) | System-wide | 4 mg/L (MCLG) | Within the limit |
| Bromate | Disinfection byproducts | 0–0 ug/L (Range) | System-wide | 0 ug/L (MCLG) | None detected |
| HAA5 | Disinfection byproducts | 4.8–9 ug/L (Range) | System-wide | 0 ug/L (MCLG) | Detected — no federal limit |
| TTHM | Disinfection byproducts | 17.4–36.3 ug/L (Range) | System-wide | 0 ug/L (MCLG) | Detected — no federal limit |
| Fluoride | Inorganic chemicals | 0.5–0.8 mg/L (Range) | System-wide | 4 mg/L (MCL) | Within the limit |
| Nitrate | Inorganic chemicals | 0.1–0.8 mg/L (Range) | System-wide | 10 mg/L (MCL) | Within the limit |
| Nitrite | Inorganic chemicals | 0–0.05 mg/L (Range) | System-wide | 1 mg/L (MCL) | Within the limit |
| Barium | Metals | 43–52 ug/L (Range) | System-wide | 2 ug/L (MCL) | At or above the limit |
| Copper | Metals | 0–1300 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Lead | Metals | 0–90 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Selenium | Metals | 0.8–1.3 ug/L (Range) | System-wide | 50 ug/L (MCL) | Within the limit |
| Total Coliform | Microbial | 99.9 % (Range) | System-wide | 95 % (MCL) | At or above the limit |
| Hexafluoropropylene oxide dimer acid | PFAS ("forever chemicals") | 0.1–0.3 (Range) | System-wide | No federal limit | Detected — no federal limit |
| Perfluorobutanesulfonic acid | PFAS ("forever chemicals") | 0.1–0.3 (Range) | System-wide | No federal limit | Detected — no federal limit |
| Perfluorohexanesulfonic acid | PFAS ("forever chemicals") | 0.1–0.3 (Range) | System-wide | No federal limit | Detected — no federal limit |
| Perfluorononanoic acid | PFAS ("forever chemicals") | 0.1–0.3 (Range) | System-wide | No federal limit | Detected — no federal limit |
| PFOA | PFAS ("forever chemicals") | 0–3 ng/L (Range) | System-wide | 0 ng/L (MCLG) | Detected — no federal limit |
| PFOS | PFAS ("forever chemicals") | 0–1.9 ng/L (Range) | System-wide | 0 ng/L (MCLG) | Detected — no federal limit |
| TOC | Physical & aggregate | 0.8–1.8 (Range) | System-wide | No federal limit | 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.
- **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.
- **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.
- **Nitrite** — A compound from fertilizer runoff, sewage, and erosion of natural deposits. Like nitrate, elevated levels can cause 'blue baby syndrome' in infants.
- **Barium** — A metal from erosion of natural deposits and industrial discharge. Long-term exposure above the federal limit can raise blood pressure.
- **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.
- **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.
- **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.
- **Hexafluoropropylene oxide dimer acid** — HFPO-DA ('GenX chemicals'), a newer-generation PFAS replacement compound. Regulated by the EPA at 10 parts per trillion and included in the PFAS Hazard Index.
- **Perfluorobutanesulfonic acid** — Perfluorobutanesulfonic acid, a shorter-chain PFAS 'forever chemical.' Has no standalone limit but is part of the EPA PFAS Hazard Index that limits PFAS in combination.
- **Perfluorohexanesulfonic acid** — Perfluorohexanesulfonic acid, a PFAS 'forever chemical.' Regulated by the EPA at 10 parts per trillion and included in the PFAS Hazard Index.
- **Perfluorononanoic acid** — Perfluorononanoic acid, a PFAS 'forever chemical.' Regulated by the EPA at 10 parts per trillion and included in the PFAS Hazard Index.
- **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.
- **PFOS** — Perfluorooctanesulfonic acid, a PFAS 'forever chemical' once used in firefighting foam and coatings. Linked to cancer, thyroid disease, and immune effects; the EPA set an enforceable limit of 4 parts per trillion.
- **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.

## 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._