Arsenic in Washington well water
In Washington, 8% of 4,117 tested private well samples exceeded the EPA limit for arsenic (10 ug/L).
Arsenic occurs naturally in New England bedrock and dissolves into well water. Long-term exposure raises the risk of bladder, lung and skin cancers, and is linked to heart disease and lower IQ in children. It has no taste or smell, so testing is the only way to know.
Check your arsenic number
Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.
Test your Washington well for arsenic
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
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Systems that remove arsenic
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Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For arsenic
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For arsenic
Whole-house arsenic and uranium filter
whole-house, at the point of entry, about $2,500
Adsorptive iron-based media; sized to your well yield.
For arsenic
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.
Where to get a well tested for arsenic in Washington: certified labs, state programs and prices.
By county, from individual samples
Public monitoring samples against the EPA limit (10 ug/L); counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Grant | 143 | 98% | 4.9 | 116 ug/L | |
| King | 266 | 77% | 2.15 | 389 ug/L | |
| Snohomish | 300 | 64% | 2 | 280 ug/L | |
| Franklin | 100 | 100% | 4.1 | 17.7 ug/L | |
| Ferry | 129 | 61% | 3 | 15 ug/L | |
| Whatcom | 80 | 78% | 0.14 | 300 ug/L | |
| Stevens | 623 | 92% | 3 | 99.4 ug/L | |
| Benton | 206 | 93% | 4.5 | 18 ug/L | |
| Kitsap | 107 | 65% | 2 | 47.4 ug/L | |
| Pierce | 188 | 63% | 0.65 | 21 ug/L | |
| Adams | 42 | 95% | 4.3 | 15.7 ug/L | |
| Thurston | 303 | 80% | 3.3 | 21 ug/L | |
| Okanogan | 397 | 61% | 2 | 25.4 ug/L | |
| Skagit | 31 | 23% | 0 | 14 ug/L | |
| Cowlitz | 54 | 98% | 1 | 13 ug/L |
- Arlington CCD, Snohomish County32% of 34
- Seattle East CCD, King County25% of 102
- Mattawa-Royal City CCD, Grant County20% of 50
- Pasco North CCD, Franklin County17% of 48
- Snoqualmie Valley CCD, King County15% of 84
- Colville Reservation CCD, Ferry County13% of 126
- Monroe CCD, Snohomish County13% of 30
- Spokane Reservation CCD, Stevens County11% of 607
- Stanwood CCD, Snohomish County10% of 62
- Connell CCD, Franklin County10% of 42
- Hanford Site CCD, Benton County9% of 199
- Tacoma CCD, Pierce County7% of 107
- Poulsbo CCD, Kitsap County7% of 57
- Bremerton CCD, Kitsap County6% of 47
- Olympia CCD, Thurston County5% of 256
- Puyallup CCD, Pierce County5% of 41
- Colville Reservation CCD, Okanogan County4% of 370
- Yakima CCD, Yakima County2% of 48
- Spokane CCD, Spokane County2% of 117
- Liberty Lake CCD, Spokane County<1% of 126
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. arsenic counts and shares are listed on each county and town page with their sources.
Analysis: Arsenic in private wells, state by state, from the same public records.