Buying a House With a Private Well in Snohomish or King County (2026)

Short answer: No state or Snohomish County rule requires a well inspection when you buy a house with an existing well, but your lender may require one or a water test. Either way, it’s worth doing yourself. Use your inspection period to test for coliform bacteria, nitrate and arsenic, pull the well log from Ecology, check that the well is far enough from the septic system, and read the water section of the seller disclosure. If the well is shared, get the written agreement and easement before you remove your contingency.

This is general information. Ask your lender what it requires for your loan, and contact the county health department about local rules for the property.

What’s required and what’s just a good idea

The Snohomish County Health Department’s handout for homebuyers says there are "no state or local well inspection requirements" for a sale involving an existing well, but lenders "may require a well inspection or water quality sampling." The state Department of Health says that in most counties, the county health or planning department or the lender may require the seller to provide water-sampling results. Ask your lender early so the test fits inside your deadlines.

The Snohomish County Health Department doesn’t inspect existing wells and no longer runs water tests. Both Snohomish County and Public Health – Seattle & King County point people to Ecology’s search tool for state-accredited labs. King County notes that lab staff can tell you how to collect samples.

What to test for

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Based on: Snohomish County Health Department, Homebuyers & Private Wells (revised 6/27/24) and Water Testing page, and Washington State Department of Health, Testing Your Water.

If the house has a filtration or treatment system, ask what it treats and for its service records. The disclosure form asks whether a treatment system is leased or owned. If it’s leased, ask for the lease terms before you remove your contingency.

Find the well’s history

A well log, or well report, records how and where the well was built and how much water it produced. Ecology’s Well Report Viewer lets you search on a map or by text, including a partial owner name or address. Drillers have to send in the report within 30 days after finishing the well. Ecology warns that most reports are historical documents that may not be accurate, complete or legible, and that locations are only accurate to the township, section and range, so the closest report on the map may not be your well.

In Snohomish County, the Health Department also keeps records for wells it reviewed as a drinking water source and you can request them by phone or email.

Check the distance to the septic system

Many homes with wells also have septic systems. State well construction rules in WAC 173-160-171 set minimum distances for a new well, including 50 feet from a septic tank and 100 feet from the edge of a drainfield or reserve drainfield area. An older well may predate the current rule. A site plan, the septic as-built drawing and the well log together can tell you how close they are. Your inspector or the county can help you read them.

Read the water section of the seller disclosure

Section 2 of the Washington seller disclosure statement asks:

• Whether the water comes from a private or public water system, a private well serving only the property, or another water system, and if shared, whether there are written agreements.
• Whether there’s a recorded or unrecorded easement for access to or maintenance of the water source.
• Whether there are problems or repairs needed, and whether the source has provided an adequate year-round supply of potable water during the seller’s ownership.
• Whether there’s a water treatment system, and whether it’s leased or owned.
• Whether there are water rights tied to the domestic supply, and whether any part of a water right has gone unused for five or more years in a row.

RCW 64.06.020 currently has two versions on the Legislature’s site: one marked effective until January 1, 2027, and one effective January 1, 2027. The questions quoted here appear in both. If your sale runs across the new year, check which form is being used.

Shared wells and small water systems

Based on: WAC 246-291-005 (Group B scope), DOH Group B Water Systems page and the seller disclosure form, RCW 64.06.020.

Public Health – Seattle & King County says private well and Group B users are responsible for testing their own water and recommends testing for bacteria and nitrate at least once a year.

Water rights, in plain terms

Most single-home wells run under the groundwater permit exemption in RCW 90.44.050. Ecology lists four exempt uses: domestic use up to 5,000 gallons per day, watering a lawn or garden of half an acre or less, industrial use up to 5,000 gallons per day, and stockwater. One exempt use of each type is allowed per project, and water from more than one well counts toward the same limit. Ecology also notes that local governments and other rules can add limits. If you plan a bigger garden, an ADU or livestock, ask before you buy.

What if there’s an old well you won’t use?

The Snohomish County Health Department says abandoned wells have to be decommissioned, including a well you’d stop using after connecting to public water. If the property has an old well, ask whether it was properly decommissioned and who pays if it wasn’t.

Fit it into your inspection period

A well check is a separate job from what a standard home inspection covers. The Snohomish County handout suggests asking what a well inspection covers. Generally it should include checking the well and its parts, testing whether it produces enough water, and sampling the water quality. Order it as soon as you’re under contract so results come back before your contingencies deadlines, since your earnest money can be at stake if you miss them. If the results are poor, you can ask the seller for repairs or treatment, renegotiate, or end the deal under your contingency.

FAQ

Is a well inspection required to buy a house in Washington?

Not by the state or Snohomish County. The Snohomish County Health Department says there are no state or local well inspection requirements for a sale involving an existing well, though lenders may require a well inspection or water sampling. The Department of Health says that in most counties the county health or planning department, or the lender, may require the seller to provide water-sampling results.

What should I test well water for when buying a house?

At a minimum, the Snohomish County Health Department recommends testing an existing well for coliform bacteria, nitrate and arsenic. Its handout lists the drinking water limits as zero coliform present, 10.0 mg/L for nitrate and 0.010 mg/L for arsenic. Your lender may require more.

How do I find the well log for a house?

Search the Department of Ecology’s Well Report Viewer by map or by owner name or address. Drillers have to submit well reports within 30 days after finishing a well, but Ecology says many reports are historical and may not be accurate or complete, and locations are only accurate to the township, section and range. In Snohomish County, the Health Department may also have records from when the well was approved as a drinking water source.

Does a private well need a water right in Washington?

Most single-home wells don’t need a water right permit. Under RCW 90.44.050, domestic use up to 5,000 gallons a day and watering a lawn or noncommercial garden up to half an acre are exempt from the permit requirement. Ecology says the limits apply to a whole project, even if water comes from more than one well, and local rules can add restrictions.

What if the house shares a well with a neighbor?

Ask whether there’s a written well-sharing agreement and a recorded easement for access and maintenance. The Washington seller disclosure form asks both questions. A well serving one or two connections usually isn’t regulated as a Group B public water system, but local health boards can adopt rules for them, so check with the county.

Talk it through with a local agent

Peter Kim and Odigo Real Estate Club can help you schedule well testing inside your inspection period, read the well log and disclosure, and negotiate if the results come back poor, with 25+ years combined experience, 593+ closings, and 122 five-star Zillow reviews. See our home buying services.

Odigo Real Estate Club · REAL Brokerage, WA #112064 · 16108 Ash Way, Suite 201, Lynnwood, WA 98087 · (425) 409-3823 · Mon–Sat 9 AM–6 PM, closed Sunday

Sources

• Snohomish County Health Department, Homebuyers & Private Wells (revised 6/27/24) (no state or local inspection requirement for existing wells; lenders may require; coliform, nitrate and arsenic limits; well records; decommissioning), https://www.snohd.org/DocumentCenter/View/14213 , accessed Nov 2, 2026.
• Snohomish County Health Department, Maintaining Your Well (homebuyers and private wells; abandoned wells), https://snohd.org/710/Maintaining-Your-Well , accessed Nov 2, 2026.
• Snohomish County Health Department, Water Testing (no longer provides water testing; routine coliform testing triggers; lab search), https://www.snohd.org/186/Water-Testing , accessed Nov 2, 2026.
• Washington State Department of Health, Testing Your Water (annual coliform and nitrate testing; retest nitrate at 5 mg/L; arsenic twice; sale-related sampling), https://doh.wa.gov/community-and-environment/drinking-water/contaminants/testing-your-water , accessed Nov 2, 2026.
• Washington State Department of Health, Private Wells: Important Information for Private Well Owners (331-349) (testing guidance and permit exemption summary), https://doh.wa.gov/sites/default/files/legacy/Documents/Pubs/331-349.pdf , accessed Nov 2, 2026.
• Public Health – Seattle & King County, Testing your water quality (private well and Group B users test their own water; bacteria and nitrate at least yearly; accredited labs), https://kingcounty.gov/en/dept/dph/health-safety/environmental-health/healthy-water-air-soil/drinking-water/water-quality/testing , accessed Nov 2, 2026.
• Washington State Department of Ecology, Well report viewer (well log search; 30-day filing; accuracy and location limits), https://ecology.wa.gov/regulations-permits/guidance-technical-assistance/well-report-viewer , accessed Nov 2, 2026.
• Washington State Department of Ecology, Groundwater permit exemption (four exempt uses; one per project; local limits), https://ecology.wa.gov/water-shorelines/water-supply/water-rights/groundwater-permit-exemption , accessed Nov 2, 2026.
• Washington State Department of Ecology, Testing drinking water (accredited lab search; sale-related sampling), https://ecology.wa.gov/water-shorelines/water-supply/wells/testing-drinking-water , accessed Nov 2, 2026.
• Washington State Department of Health, Group B Water Systems (fewer than 15 connections and 25 people; local health jurisdiction rules), https://doh.wa.gov/community-and-environment/drinking-water/water-system-assistance/group-b , accessed Nov 2, 2026.
• Washington State Legislature, WAC 246-291-005 (Group B rule scope; one- and two-connection systems), https://app.leg.wa.gov/wac/default.aspx?cite=246-291-005 , accessed Nov 2, 2026.
• Washington State Legislature, WAC 173-160-171 (minimum well setbacks from septic tanks and drainfields), https://app.leg.wa.gov/wac/default.aspx?cite=173-160-171 , accessed Nov 2, 2026.
• Washington State Legislature, RCW 90.44.050 (groundwater permit exemption), https://app.leg.wa.gov/RCW/default.aspx?cite=90.44.050 , accessed Nov 2, 2026.
• Washington State Legislature, RCW 64.06.020 (seller disclosure statement form; version effective until Jan 1, 2027 and version effective Jan 1, 2027), https://app.leg.wa.gov/RCW/default.aspx?cite=64.06.020 , accessed Nov 2, 2026.

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