Well water in Douglas County, Washington

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Testing recommended

tested well samples in Douglas County exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal.

419 test results across 15 contaminants from at least 40 wells, 1959 to 2024; nitrate has the most at 67. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

An estimated 8,048 people in Douglas County get their drinking water from a private well, per USGS 2015 county water use. That is about 20% of residents.

Separately, the USGS national arsenic model estimates that 5% of the 8,048 people on private wells in Douglas County draw water above 10 ug/L (the model's range is 4% to 7%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Douglas County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Above limit	Samples	Detected	Median	Highest	Limit
Nitrate 1959 to 2024	15%	67	99%	2.3	33	10 mg/L EPA limit
Fluoride 1959 to 2024	0%	58	100%	0.225	2	4 mg/L EPA limit
Copper 1970 to 2024	0%	17	53%	0	0.022	1.3 mg/L EPA limit
Lead 1970 to 2024	0%	16	56%	0	0.953	15 ug/L EPA limit
Chloride 1959 to 2024	no limit	60	100%	5.35	100	250 mg/L nuisance level
Sodium 1959 to 2024	no limit	58	100%	15.5	64	20 mg/L health guideline
Iron 1959 to 2024	no limit	57	67%	3.7	1,600	300 ug/L nuisance level
Manganese 1970 to 2024	no limit	51	51%	0	237	300 ug/L health guideline

Sampled fewer than 10 times, too few to summarize: Arsenic (9), Radium (226 + 228) (6), Uranium (6), E. coli (4), PFOS (2), PFOA (2), Radon (6).

Over time

Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.

Contaminant	before 2000	2000s	2010s	2020s
Nitrate	15%47 samples	10%10 samples	n/a	n/a

Closer than the county

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

The contaminants most often above their limit here are nitrate (15% of 67 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Chloride, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Douglas County

1
Nitrate
15% of 67 local samples were above the limit.
2
Coliform bacteria
Recommended for every private well, every year.
3
Radon
Median local reading is 635 pCi/L.
4
Fluoride
Detected in 100% of local samples.
5
Chloride
Detected in 100% of local samples.
6
Iron
Detected in 67% of local samples.
7
Copper
Detected in 53% of local samples.
8
Volatile organic compounds (VOCs)
2 reported spills and releases on record locally.

Test your Douglas County well for nitrate, coliform bacteria and radon

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 $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in Washington: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Douglas County numbers, $29. Every line explained, ranked by what matters, with the fix for each.

Wells in Douglas County

1,391 domestic wells in Douglas County are on record with the state since 1993. the typical well is 184 feet deep (one in ten goes past 498 feet).

In a typical Douglas County well, the median yield is 16 gallons per minute.

236

1990s

466

2000s

388

2010s

295

2020s

Find your own well's report

The state keeps the driller's report for most wells drilled since 1984. It tells you how deep your well is, where bedrock starts, and how much water it makes, which decides what treatment can work.

Open Ecology well report search and choose Water Well.
It lists depth, casing, static water level, the yield test and the driller.

Washington has required well reports since 1971; reports are located only to the quarter-quarter section, so check the address on the scan.

The rock under Douglas County

Columbia Plateau basin-fill aquifers

Unconsolidated sand and gravel. Wells in sand and gravel are usually shallow and productive, and they recharge quickly from the surface. That makes them the most exposed to nitrate, bacteria and anything spilled nearby, and the least likely to carry arsenic or radon from the rock.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.

Official help in Washington

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Drinking Water, Washington State Department of Health
Environmental lab accreditation, Washington State Department of Ecology

Contamination sources on record in Douglas County

Washington Ecology facility interactions records 2 reported spills and releases in Douglas County, among 221 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

2: reported spills and releasesMost spills are fuel; a few are solvents or chemicals that reach the water table.
199: other remediation projects
20: other solid waste facilities

Treatment that fits the local profile

Nitrate

Point-of-use reverse osmosis; Anion exchange; Distillation

Systems we would look at first

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 nitrate

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For nitrate

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.

Free, no obligation

Get on the list for a free in-home water test in Douglas County

No water treatment company serves Douglas County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Douglas County, and you get an email naming it first.

Common questions

How deep are wells in Douglas County?

The typical domestic well in Douglas County is 184 feet deep, based on 1,391 wells reported to the state since 1993. One in ten is deeper than 498 feet.

How often should I test a private well in Douglas County?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Counties near Douglas County

Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.

Want the numbers themselves? Download the Washington dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 419 samples in Douglas County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 8,048 people on private wells in Douglas County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
Washington Ecology well construction reports: 1,392 well records in Douglas County, 1,391 domestic. Well construction reports filed with the Washington State Department of Ecology, water wells only, located at the quarter-quarter section. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 17, 2026.
Washington Ecology facility interactions: 221 regulated sites located in Douglas County. Toxics cleanup sites, spills and solid waste facilities from the Washington State Department of Ecology Facility/Site register. Retrieved September 17, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.