Select a city below to view local well water testing services in your area. Each city page lists providers offering lab testing, field sampling, or mail-in well water tests.
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Washington has significant private well usage, particularly in rural areas east of the Cascades and in some western Washington communities. The state's geology varies dramatically from the volcanic Cascades to the Columbia Plateau to the Puget Sound lowlands.
Washington does not have a statewide mandate requiring private well water testing at property sale. The state takes a recommendation-based approach, with guidance from the Washington State Department of Health (DOH) and local health jurisdictions.
Known contaminants of concern vary by region. Arsenic occurs naturally in some areas. Nitrates can be elevated in agricultural regions. Testing is essential to know what's in your specific well.
Washington does not have a statewide law requiring private well water testing for all property sales. Testing is recommended but generally voluntary for existing private wells.
For new well construction, testing requirements apply. The well must be tested before approval for use. Requirements are administered through local health jurisdictions under state rules.
Washington DOH recommends annual testing for all private well owners. The baseline recommendation is annual testing for bacteria and nitrates, with additional testing based on location.
Real estate transactions often include testing. Mortgage lenders frequently require water quality documentation. Many buyers request testing during due diligence.
DOH recommends annual testing for bacteria (total coliform and E. coli) and nitrates as a minimum. These baseline parameters apply to all Washington well owners.
Arsenic occurs naturally in some Washington groundwater, particularly in certain areas east of the Cascades. It's odorless and tasteless, so testing is the only way to detect it.
Agricultural areas-particularly in central and eastern Washington-may have elevated nitrate levels due to farming activities. If you're in an agricultural area, nitrate testing is especially important.
Consider testing for: lead (especially with older plumbing), arsenic (some areas), radon in water (some areas), and any contaminants your local health jurisdiction identifies.
Every year
At least once, repeat every 3-5 years
Based on location and circumstances
Well water testing costs in Washington depend on what you're testing for and which provider you use. Basic bacteria and nitrate tests are generally affordable. Adding arsenic, comprehensive panels, or specialty tests increases the cost.
Local health jurisdictions may provide or facilitate well water testing. Private certified labs serve Washington well owners across the state. The Washington State Public Health Laboratory may offer some services.
Turnaround time follows typical patterns: bacteria results within a few days (samples are time-sensitive), chemical tests within 5-10 business days.
For new well construction, coordinate with your local health jurisdiction for required testing. For real estate transactions, plan ahead to allow adequate time.
Washington well owners can choose from certified laboratories, local health jurisdiction programs, and mail-in test kit providers. For accurate, defensible results, use labs accredited for drinking water analysis.
Local health jurisdictions (county or district) are valuable resources. They may offer testing, maintain lists of certified labs, and understand local groundwater conditions.
Given Washington's varied geology, local knowledge matters. Eastern Washington has different considerations than the Puget Sound region. Your local health jurisdiction can advise on concerns for your area.
Washington DOH provides resources for private well owners. Using accredited labs ensures your results are reliable.
Quick answers to common questions about testing well water in Washington, from requirements to regional concerns.