# Rockville, MD — Drinking Water Quality

> Contaminant levels for the Rockville, MD public water system, transcribed from its annual Consumer Confidence Report and compared to federal limits.

- Page: https://www.thewatermap.com/water/rockville-md
- JSON API: https://www.thewatermap.com/api/water/rockville-md
- Source: the utility's annual Consumer Confidence Report (CCR)
- Verification: transcribed by a model, cross-checked by a second model, approved by a human
- Contaminants measured: 17
- Contaminants with a federal limit: 16
- 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 | 1.32 mg/L (Reported level) | System-wide | 4 mg/L (MCLG) | Within the limit |
| HAA5 | Disinfection byproducts | 44 ug/L (Range) | System-wide | 60 ug/L (MCL) | Approaching the limit |
| TTHM | Disinfection byproducts | 122 ug/L (Range) | System-wide | 80 ug/L (MCL) | At or above the limit |
| Fluoride | Inorganic chemicals | 0.64 mg/L (Range) | System-wide | 4 mg/L (MCLG) | Within the limit |
| Nitrate | Inorganic chemicals | 1.3 mg/L (Range) | System-wide | 10 mg/L (MCLG) | Within the limit |
| Barium | Metals | 0.037 mg/L (Reported level) | System-wide | 2 mg/L (MCLG) | Within the limit |
| Copper | Metals | 0.56 mg/L (Range) | At the tap | 1.3 mg/L (MCLG) | Within the limit |
| Lead | Metals | 4 ug/L (Range) | At the tap | 0 ug/L (MCLG) | Detected — no federal limit |
| Escherichia coli (E. coli) | Microbial | 3 (Reported level) | System-wide | 0 (MCLG) | Detected — no federal limit |
| Hexafluoropropylene oxide dimer acid | PFAS ("forever chemicals") | 0 (Range) | System-wide | 10 (MCL) | None detected |
| Perfluorohexanesulfonic acid | PFAS ("forever chemicals") | 1.9 (Range) | System-wide | 10 (MCL) | Within the limit |
| Perfluorononanoic acid | PFAS ("forever chemicals") | 0.57 (Range) | System-wide | 10 (MCL) | Within the limit |
| PFBA | PFAS ("forever chemicals") | 2.8 (Range) | System-wide | 10 (MCL) | Within the limit |
| PFOA | PFAS ("forever chemicals") | 2.6 (Range) | System-wide | 4 (MCL) | Approaching the limit |
| PFOS | PFAS ("forever chemicals") | 3.19 (Range) | System-wide | 4 (MCL) | Approaching the limit |
| Turbidity | Physical & aggregate | 0.26 NTU (Range) | System-wide | No federal limit | Detected — no federal limit |
| Atrazine | VOCs & pesticides | Not detected ug/L (Reported level) | System-wide | 3 ug/L (MCLG) | None detected |

## 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.
- **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.
- **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.
- **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.
- **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.
- **PFBA** — Perfluorobutanoic acid, a shorter-chain PFAS 'forever chemical.' Monitored under EPA rules; persistent in the environment and the human body.
- **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.
- **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.
- **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.

## 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 2026-05-21 from thewatermap.com._