Private well guide

Well Water in Washington: Testing, Rules, Labs and Licensed Contractors

409,542 households in Washington get their water from a private well. Here is what the state requires, where to get it tested, and who is licensed to work on it.

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215Licensed contractorschecked against state records
38Certified labsfrom the state certified list
39Counties covered
409,542Households on wells14% of households (est.)

About one Washington household in seven drinks from a private well, and outside the Puget Sound cities the share is closer to one in two. The state keeps a tight hand on how a well is drilled and who drills it, files a report on every one, and then leaves the water to the owner and the county.

Who is in charge of a Washington well

The Department of Ecology owns the well itself. Before a hole is started the driller files a notice of intent and pays a fee to Ecology, the driller must hold an Ecology water well operator license, the well must meet the construction standards in chapter 173-160 WAC, and a well report goes to Ecology within 30 days and becomes public in the well report map. A household well pumping under 5,000 gallons a day needs no water right, though since 2018 new domestic wells in some watersheds pay a mitigation fee and face limits. Water quality belongs to the Department of Health and the county health departments: they set the potable-water proof a county wants before it issues a building permit, they run most of the local labs, and they answer the phone when a test comes back bad.

What is required, and what is left to you

A licensed driller, the notice of intent, construction to the standard and the well report. Ecology does not test the water. Your county almost certainly will ask for a coliform and nitrate result before it approves a house on the new well, and that is usually the only test the well ever gets unless you keep it up. The Department of Health’s advice is coliform bacteria every year, nitrate every three years and arsenic at least once, because arsenic turns up in Washington groundwater more often than most owners expect. Nothing is required when a home is sold.

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.

What the water is like

West of the Cascades most wells tap glacial sand and gravel, where the usual problems are iron and manganese staining, arsenic in the deeper glacial layers around Puget Sound, and bacteria in the shallow and dug wells that are still common in the older counties. Island and shoreline wells in San Juan, Island, Kitsap and Jefferson counties can turn salty as they are pumped. East of the mountains the Columbia Plateau basalt gives hard, alkaline water, sometimes with fluoride and sodium from depth, and the farm valleys carry nitrate: the Lower Yakima Valley and the Sumas-Blaine aquifer in Whatcom County are the two areas where the state has had to step in. The granite country of Okanogan, Stevens and Spokane counties adds uranium and radon. A broad first test tells you which of these is yours.

Ecology-accredited labs and county health labs

Washington accredits environmental labs through Ecology’s Laboratory Accreditation Program, and its lab search marks the labs that accept samples from the public. Every lab below holds current drinking water accreditation and takes public samples. The county health department labs are the cheapest route for the yearly coliform test and usually run nitrate as well; the commercial labs handle arsenic, metals, uranium and the wider panel, and most will mail bottles anywhere in the state.

38 certified labs

See all 38 certified labs in Washington

Licensed water well drillers

Washington licenses the driller, not the company. Every profile below is built from an active Ecology water well operator license, grouped under the drilling company Ecology lists for the licensee, with each licensed driller named. Because Ecology publishes every well report with the driller’s license number, the profiles also show how many water wells the company has reported since 2016 and in which counties, which is the most reliable guide to who is actually drilling near you. Pump work is not licensed by the state; most drilling companies do it, and pump-only companies are not on this list.

215 licensed contractors

See all 215 licensed contractors in Washington

By county

Well use runs from about 6% of homes in King County and under 8% in Pierce, Pacific and Asotin to roughly half in Lewis, Stevens and Okanogan counties, more than half in San Juan, and about two thirds in Pend Oreille and Ferry. Each county page carries its well population, the nearest accredited labs and the licensed drillers based there.

Washington well water questions

Do I need a permit to drill a well in Washington?

Not a permit as such, but three things that work like one: the driller files a notice of intent with Ecology before drilling, a household well under 5,000 gallons a day is exempt from a water right (with mitigation fees and limits in some watersheds since 2018), and your county needs proof of adequate potable water before it issues a building permit. Your licensed driller handles the Ecology side.

Is a water test required when I sell my house?

No statewide. Lenders on government-backed loans require a bacteria, nitrate and lead test before closing, and a few counties require a well inspection or test at transfer, so ask your county health department.

How do I find the record for my well?

Use Ecology’s well report map: search by address or parcel and open the well report, which shows the depth, casing, seal, static water level and yield. Almost every well drilled since the 1970s has one.

Which lab should I use?

Any lab on Ecology’s accredited list that accepts public samples. Use a county health lab for the yearly coliform and nitrate check and a commercial lab for arsenic, metals, uranium or PFAS.