Arsenic in Drinking Water — St Charles County Pwsd 2...
St Charles County Pwsd 2 · Lake Saint Louis, MO · 100,587 people served
Data: EPA SDWIS, ECHO, 2024 Consumer Confidence Report
Arsenic Detected in ST CHARLES COUNTY PWSD 2
Arsenic was detected at 388 ppb in the ST CHARLES COUNTY PWSD 2 water system serving Lake Saint Louis, O Fallon (MO), exceeding the EPA limit of 10 ppb.
This system serves approximately 100,587 people across 3 ZIP codes.
Data source: 2024 Consumer Confidence Report (CCR) and EPA SDWIS/ECHO.
Detected Levels
| Contaminant | Level Detected | EPA Limit | Status |
|---|---|---|---|
| Arsenic | 388 ppb | 10 ppb | Violation |
Health Effects of Arsenic
The EPA classifies arsenic as a Group A human carcinogen. Long-term exposure to arsenic in drinking water — even at levels below the MCL — increases the risk of bladder, lung, skin, kidney, and liver cancer. Non-cancer effects include cardiovascular disease, diabetes, skin lesions (darkening and thickening), peripheral neuropathy, and immune system suppression. Children exposed to arsenic may experience cognitive development problems.
Source: ATSDR — Arsenic Toxicological Profile; EPA.
EPA Standard
The EPA maximum contaminant level (MCL) for arsenic is 10 ppb, governed by the Arsenic Rule (2006). Water systems that exceed this limit must notify consumers and take corrective action.
What You Can Do
- Install a reverse osmosis system — the most reliable arsenic removal technology for homes
- Use a point-of-use filter certified to NSF 53 for arsenic reduction
- Have your water tested by an EPA-certified lab — especially if you use a private well
- If arsenic is naturally occurring in your area, consider whole-house treatment
- Do not rely on standard carbon filters — most do not remove arsenic
- If on a private well, test annually; arsenic levels can fluctuate seasonally
Recommended Water Filters
The most effective treatment for arsenic removal is Reverse Osmosis.
| Filter Type | Effectiveness | NSF Standard | Notes |
|---|---|---|---|
| Reverse Osmosis (RO) | 95-99% | NSF 58 | Most effective for both arsenate (As V) and arsenite (As III) |
| Adsorptive Media (iron-based) | 90-95% | NSF 53 | Effective for arsenate; may need pre-oxidation for arsenite |
| Distillation | 98%+ | NSF 62 | Very effective but impractical for large volumes |
ZIP Codes Served by This System
Check water quality for your specific ZIP code:
Related Resources
- ST CHARLES COUNTY PWSD 2 — Full Water System Profile
- Arsenic in Drinking Water — Overview
- EPA: Arsenic
Detected Levels
| Contaminant | Level Detected | EPA Limit | Status |
|---|---|---|---|
| Arsenic | 388 ppb | 10 ppb | Violation |
Recommended Water Filters
The most effective treatment for arsenic removal is Reverse Osmosis.
| Filter Type | Effectiveness | NSF Standard | Notes |
|---|---|---|---|
| Reverse Osmosis (RO) | 95-99% | NSF 58 | Most effective for both arsenate (As V) and arsenite (As III) |
| Adsorptive Media (iron-based) | 90-95% | NSF 53 | Effective for arsenate; may need pre-oxidation for arsenite |
| Distillation | 98%+ | NSF 62 | Very effective but impractical for large volumes |