The Okanogan County Public Health (OCPHD) water laboratory in Okanogan tests drinking water and posts lab-slip instructions for both private wells and public water systems.
Tests. Coliform bacteria and nitrate.
Prices. Fees published on the county’s water testing page (viewed 2026-10-24): $35 per coliform sample and $45 per nitrate sample, non-refundable.
Bottles and drop-off.
- Empty bottles are free at your local city hall or the OCPHD office in Okanogan.
- Bring samples to the OCPHD front counter before 3pm: coliform Monday to Thursday, nitrate Monday to Wednesday, from 7:30am. No samples on Fridays, and mailed samples are not accepted.
- Coliform samples must be under 30 hours old and nitrate samples under 45 hours old. Nitrate samples must be kept cold.
- On the first Monday of each month, samples are collected from the Oroville, Tonasket, Brewster, Pateros, Winthrop and Twisp city halls during set morning hours (Tuesday if Monday is a holiday).
Accreditation. Ecology accreditation H478 (current certificate H478-26), covering coliform and E. coli and nitrate in drinking water.