Oregon Well Water Testing Requirements
Oregon Revised Statute 448.271 — the Oregon Domestic Well Act — requires water quality testing when selling a home on a private well. Here is what buyers, sellers, and real estate agents need to know.
6 min read · Waterlab Corp Laboratory Staff
Real estate transaction? Call Waterlab Corp at 503-363-0473 as soon as your listing goes active. Results take 1–5 business days and must be in hand before closing.
Who must comply
Any seller of a residential property served by a private domestic well must provide a copy of a water quality test to the buyer before closing. This applies to single-family homes, manufactured homes on private wells, and parcels where the well is the primary water source.
Which tests are required
Oregon law requires testing for total coliform bacteria and nitrate at minimum. Many real estate transactions also include arsenic, given its prevalence in Oregon groundwater, and hardness. Lenders (FHA, VA, USDA) may require additional tests — always confirm with your lender early in the transaction.
The lab must be ORELAP-accredited
Results are only valid under ORS 448.271 if they come from a laboratory accredited by the Oregon Environmental Laboratory Accreditation Program (ORELAP). Waterlab Corp holds ORELAP accreditation #100039. Home test kits from hardware stores do not qualify.
Timing and validity
The test must be conducted within 12 months prior to closing. Oregon does not specify a minimum sample age, but best practice is to test as early in the transaction as possible so there is time to address any problems before closing.
What if results show contamination
A positive coliform or nitrate result above the MCL does not automatically kill a transaction, but it must be disclosed. Options include treatment system installation, re-testing after treatment, price negotiation, or well remediation. Waterlab Corp staff can advise on follow-up sampling protocols.
Seller vs. buyer responsibilities
Oregon law places the testing obligation on the seller. However, buyers often request additional tests beyond the legal minimum. Buyers should request the test results early and review them with their agent and, if results are borderline, with a water quality professional.
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