Washington county well guide

Well Water in San Juan County, WA: Testing, Contractors and Rules

About 3,514 households in San Juan County, 54% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
54%of households on a private well
Share on wells, county vs state
San Juan County54%
Washington average14%
9licensed contractors serve the county
26 mito the nearest certified lab, Exact Scientific Services, Inc.
Nostatewide test required when a home is sold

Most homes in San Juan County are on a private well: about 3,514 households, 54% of the county. That makes San Juan County one of the places in Washington where the water department is the homeowner.

Local rules for wells in San Juan County

Private wells in San Juan County follow Washington's statewide rules, administered by Washington Department of Ecology, Well Construction and Licensing Program. No water test is required by the state when a new well is completed. There is no statewide test requirement when a home is sold, though lenders often ask for one. The cards below show the details and the official sources.

At a glance

Water test for a new wellNot required statewide

No statewide water test from Ecology. What the state requires is a notice of intent and fee filed with Ecology at least 72 hours before drilling, a licensed water well driller, construction to the chapter 173-160 WAC standards (100 ft from septic drainfields, surface seal, a well tag) and a well report filed within 30 days. The test comes in through the county: to get a building permit on a well, most counties ask for proof of potable water, which usually means a coliform bacteria and nitrate test from an accredited lab, and some add arsenic. Check with your county health department before the well is drilled.

Water test when a home is soldNot required statewide

No statewide requirement. The seller disclosure form (Form 17) only asks whether the property is on a well and whether the water has been tested. FHA, VA and USDA loans normally require a bacteria, nitrate and lead sample before closing, and a few counties require a well inspection or water test when a property with a well changes hands.

What the state recommends

The Washington Department of Health recommends testing a private well for coliform bacteria every year and for nitrate every three years, and a first-time test for arsenic, which is common in Washington groundwater. Add hardness, iron, manganese, fluoride, uranium and radon on a first panel, PFAS near military airfields and fire training sites, and test again after flooding, a change in taste, color or smell, or any work on the well.

Free or low-cost testingAvailable

No statewide free testing. A few local programs test for free or at cost: the Whatcom Conservation District tests nitrate in the Sumas-Blaine aquifer, the Lower Yakima Valley groundwater program tests nitrate in that area, and several county health departments and conservation districts run testing days. Otherwise, county health laboratories run a coliform test for roughly $25 to $50 and a nitrate test for a little more, and Ecology's lab list marks which labs accept samples from the public.

Getting your water tested near San Juan County

3 certified labs within 40 miles serve San Juan County, starting with Exact Scientific Services, Inc. in Ferndale (about 26 miles from the county center). Each card below shows whether the lab takes homeowner samples and which tests it is certified for.

3 certified labs within 40 miles

Licensed well contractors serving San Juan County

9 licensed contractors serve San Juan County, including A and A Well Drilling and Aquatech Well Drilling and Pumps. Each profile carries the state license number and the date we checked it, and the filters below sort them by drilling, pump work or treatment.

Well depth and water chemistry

Wells in San Juan County typically reach 60 to 250 ft in the glacial deposits of the Puget Sound lowland and the Columbia River valleys; 150 to 500 ft in the basalt of the Columbia Plateau and the Yakima and Walla Walla valleys; 100 to 400 ft in the fractured rock of the Cascade and Okanogan foothills, where yields are low. What comes up with the water depends on the aquifer, and across Washington the usual suspects are arsenic (puget sound lowland, whatcom, snohomish and pierce counties, parts of the columbia plateau). A first full panel tells you which of them apply to your well.

Typical well depth

Varies by location. Check the state well record search for logs of nearby wells.

Contaminants to test for
  • Arsenic (Puget Sound lowland
  • Whatcom
  • Snohomish and Pierce counties
  • Parts of the Columbia Plateau)
  • Nitrate (Sumas-Blaine aquifer in Whatcom County
  • Lower Yakima Valley
  • The Columbia Basin
  • Spokane-Rathdrum valley)
  • Coliform bacteria (shallow wells and dug wells west of the Cascades)
  • Iron and manganese (glacial deposits around Puget Sound)
  • Hardness (Columbia Plateau basalt)
  • Uranium and radon (Okanogan and Spokane County granite)
  • Fluoride and sodium (deep basalt wells)
  • Saltwater intrusion (island and coastal wells in San Juan
  • Island
  • Kitsap and Jefferson counties)
  • PFAS near military bases and airfields

Neighboring counties: Whatcom County, Island County, Skagit County, Jefferson County.

What well work costs in San Juan County

Bacteria test (coliform and E. coli)$21 to $55published Washington lab fees
Nitrate test$21 to $55published Washington lab fees
Broad panel (metals and minerals)$85 to $450state and university lab packages
Well inspection$250 to $550$350 to $900 with water testing
Submersible pump replacement$1,000 to $2,500installed; deep wells cost more
Pressure tank replacement$800 to $1,500installed
One treatment unit$700 to $3,500softener, iron filter or UV, installed
Multi-stage whole-house treatment$2,500 to $10,000+several units or whole-house RO, installed
New well, complete$6,000 to $16,000typical 200 ft well with pump; drilling alone about $20 to $30 per foot; deeper wells cost more
Shock chlorination$80 to $200by a contractor; under $30 to do yourself

Washington DOH list of certified labs; the Thurston County water lab charges $32 for each test. Installed costs are national 2026 ranges; local quotes vary with depth, access and materials. Sources, checked September 2026: Washington DOH nitrate and coliform labs, Thurston County water lab, HomeGuide cost guides, Angi: cost to shock a well.

Questions San Juan County well owners ask

How many homes in San Juan County are on a well?

About 3,514, or 54% of households, based on Census housing data and state well surveys. The share is highest outside the towns with public water.

Where is the closest certified lab to San Juan County?

Exact Scientific Services, Inc. in Ferndale, about 26 miles away. It accepts homeowner samples.

Do I need a permit to drill a well in San Juan County?

No statewide water test from Ecology. What the state requires is a notice of intent and fee filed with Ecology at least 72 hours before drilling, a licensed water well driller, construction to the chapter 173-160 WAC standards (100 ft from septic drainfields, surface seal, a well tag) and a well report filed within 30 days. The test comes in through the county: to get a building permit on a well, most counties ask for proof of potable water, which usually means a coliform bacteria and nitrate test from an accredited lab, and some add arsenic. Check with your county health department before the well is drilled.

What does a well test cost near San Juan County?

Published lab fees in Washington: $21 to $55 for a bacteria test and $21 to $55 for nitrate. Washington DOH list of certified labs; the Thurston County water lab charges $32 for each test. Mail-in kits cost about the same as walking in.