State-certified labTakes homeowner samples

San Mateo County Public Health Laboratory

San Mateo, CA · San Mateo CountyCounty health department lab

Call (650) 573-2500
WebsiteDirections
Certification
State certified
list checked September 29, 2026
Certificate
1591
California program
Tests listed
1
Coliform Bacteria
Homeowner samples
Yes
Drop-off

About San Mateo County Public Health Laboratory

San Mateo County Public Health Laboratory is a county health department lab in San Mateo, CA (San Mateo County). It is on the California drinking water program's list of certified laboratories (certificate 1591), and we last checked the list on September 29, 2026.

The lab takes samples from homeowners.

Before you go: Accredited by the California Environmental Laboratory Accreditation Program (ELAP) for drinking water fields of testing (certificate 1591): Microbiology. Accreditation expires 2027-08-31. County laboratory; the usual place for a bacteria and nitrate test on a private well. Call for bottles, drop-off days and pricing.

This profile is built from the official state list of certified drinking water laboratories, checked on September 29, 2026. Well Water Insider does not rate or endorse labs. Run this lab? Claim the profile to add prices, turnaround times, hours and a description.

Certification and services

State certified
Certification number
1591
Certified by
California drinking water program
Certified for
Microbiology
Lab type
County Health
Last verified
September 29, 2026

Listed on the official state certified laboratory list.

How to test your water here

How this lab takes samples, based on its listing. Call to confirm hours, bottles and prices.

Homeowner samplesYou can collect and drop off your own sample
Mail-in kitsNot listed, call to confirm
Walk-in drop offNot listed, call to confirm

Published lab fees in California: $38 to $61 for a bacteria test and $66 for nitrate. Sonoma County Public Health Lab ($38 bacteria) and a commercial certified lab (Caltest: $61 bacteria, $66 nitrate, $445 homeowner panel). Prices at this lab may differ.

  1. 1

    Call for the right bottles

    Bacteria samples need a sterile bottle from the lab. Chemistry samples usually take a clean container the lab supplies.

  2. 2

    Collect from a cold tap before treatment

    Skip softeners and filters. Remove the aerator, run the water 3 to 5 minutes, then fill without touching the inside of the cap.

  3. 3

    Keep it cold and deliver within 24 hours

    Bacteria samples are time-sensitive. Use a cooler with ice packs and hand it in or ship it the same day.

  4. 4

    Read the report against the standards

    Compare results with EPA drinking water limits. If anything is over, our problem pages explain what it means and how to treat it.

Tests this lab is listed for

From the state certification list and the lab's own listing. Ask which ones it runs for homeowners.

Coliform Bacteria

Total coliform and E. coli. The test the CDC recommends every year for every private well. Learn more

Location

225 37th Avenue Building A First Floor, San Mateo, CA 94403

Lab address

Questions about San Mateo County Public Health Laboratory

Is San Mateo County Public Health Laboratory state certified?

Yes. It is on the California list of laboratories certified for drinking water testing, last checked September 29, 2026.

What can San Mateo County Public Health Laboratory test well water for?

Its listing covers coliform bacteria. Call to confirm prices and which tests it runs for private well owners.

Can I bring my own well water sample?

Yes, the listing says it takes homeowner samples. Get the right bottle from the lab first, especially for bacteria.

How do I contact San Mateo County Public Health Laboratory?

Call (650) 573-2500 and visit the lab's website. The address is 225 37th Avenue Building A First Floor, San Mateo, CA 94403.

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