Certified Water Testing Labs in Washington

The Washington State Department of Ecology, through the Environmental Laboratory Accreditation Program — Environmental Laboratories Accredited for Drinking Water Analyses. The program follows the EPA's national framework for drinking water laboratory certification, which requires EPA-approved test methods, at least annual proficiency testing, and periodic on-site audits. Source: Washington State Department of Ecology — Laboratory Accreditation Program (WA ELAP; drinking water labs report to WA DOH Office of Drinking Water) (https://apps.ecology.wa.gov/laboratorysearch/appfiles/DWLabs_WAByCounty.pdf) and EPA (epa.gov/dwlabcert).

45 accredited drinking water labs are located in Washington, as of the official list we pulled on August 2, 2026. Accreditation changes throughout the year, so treat this as a starting point and confirm status with the lab. Source: Washington State Department of Ecology — Laboratory Accreditation Program (WA ELAP; drinking water labs report to WA DOH Office of Drinking Water) (https://apps.ecology.wa.gov/laboratorysearch/appfiles/DWLabs_WAByCounty.pdf).

The EPA recommends testing private wells annually for total coliform bacteria, nitrates, total dissolved solids, and pH — and testing immediately after flooding, well repairs, nearby construction, or any change in your water's taste, odor, or color. Your local health department can tell you which contaminants are common in Washington groundwater. Source: EPA, Protect Your Home's Water (epa.gov/privatewells).

This list covers labs located in Washington that were on the official list published by the Washington State Department of Ecology as of August 2, 2026. Accreditation changes during the year, so a lab missing from this page may have been accredited since then — the official source linked above always has the current list. What we'd avoid is any lab that can't show a current drinking water certification at all. The EPA's guidance is to only use certified laboratories for drinking water testing. Source: EPA, Protect Your Home's Water (epa.gov/privatewells).

Ask the lab about a mail-in collection kit — many certified labs ship one with instructions and pre-treated bottles. Timing matters for some tests (bacteria samples have a short window between collection and analysis), so follow the lab's collection instructions exactly. Your local health department is also worth a call; some offer private well testing for free. Source on health department testing: EPA, Protect Your Home's Water (epa.gov/privatewells).