Arsenic in Drinking Water — City of Redmond Water Sy...
City of Redmond Water System · Redmond, WA · 163,335 people served
Data: EPA SDWIS, ECHO, 2024 Consumer Confidence Report
Arsenic Detected in City of Redmond Water System
Arsenic was detected at 230 ppb in the City of Redmond Water System water system serving Redmond (WA), exceeding the EPA limit of 10 ppb.
This system serves approximately 163,335 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 | 230 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
- City of Redmond Water System — Full Water System Profile
- Arsenic in Drinking Water — Overview
- EPA: Arsenic
Detected Levels
| Contaminant | Level Detected | EPA Limit | Status |
|---|---|---|---|
| Arsenic | 230 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 |