About this service
The Marin County Public Health Laboratory provides testing services for private well water. Private well owners can submit water samples to the laboratory for analysis; the laboratory processes submitted samples and sends results to the contact information provided on the requisition form. For laboratory questions, contact the Public Health Laboratory at 707-784-4410 or visit the laboratory website. For other questions about well testing in Marin County, contact Marin County Public Health at 415-473-4163 or email Marin County Public Health.
Who this service is for
This service is for private well owners and residents who rely on private wells for household water and need laboratory testing of their well water. If you will submit a private well water sample for testing, you must pick up special prepared sample bottles in San Rafael.
Details
Private well water testing
Prepared sample bottles are available for pickup at Marin County Public Health, 3240 Kerner Blvd, San Rafael. Press the white doorbell labeled “Water Sample Drop Off.” Samples should be kept refrigerated, or placed in a cooler with ice packs, and dropped off to the laboratory the same day they are collected.
- Beginning 04/01/2025, sample drop-off hours are Monday to Thursday, 9 a.m. to 12 p.m., and 1 p.m. to 1:30 p.m. Nitrate samples are accepted Tuesdays only.
- If applicable, payment for well water testing can be made online via the laboratory portal: pay the well water testing fee online. See the portal for current well water testing prices.
The laboratory will process your sample and send results using the contact information on your requisition form.
Contact and additional resources
- Public Health Laboratory (lab questions): 707-784-4410. Lab website: Solano/Napa/Solano/Yolo/Marin Public Health Laboratory.
- Marin County Public Health (other questions): 415-473-4163; email: Marin County Public Health.
- Marin County Environmental Services Beach Water Monitoring questions: 415-473-7146; website: Marin County Beach Water Monitoring.