Well water testing in California
Nobody tests a private well unless the owner does. In California, the public record says to start with nitrate, arsenic, uranium, then bacteria every year. Below: what to order, where, what it costs, and the county-by-county results that set the order.
What to test for first
- 1Nitrate16% of 57,577 local samples were above the limit.
- 2Arsenic15% of 18,251 local samples were above the limit.
- 3Uranium8% of 7,553 local samples were above the limit.
- 4PFOS7% of 898 local samples were above the limit.
- 5Gross alpha6% of 382 local samples were above the limit.
Test your California well for nitrate, arsenic and uranium
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.
Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.
Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.
Where to get it tested
Three routes, and all of them work. A mail-in kit from a certified lab is the simplest: the lab ships bottles, you fill them at the kitchen tap, and results come back by email. The full panel above is $209.
A local certified lab is the second route. Environmental Laboratory Accreditation Program (ELAP) from State Water Resources Control Board lists every lab certified for drinking water in California. Call ahead: some take walk-in samples, some ship bottles.
Free or low-cost testing: The State Water Resources Control Board and Regional Water Boards fund free domestic well testing programs across many parts of the state, each with its own service area and eligibility, listed in a county-by-county directory. How to get it
For questions about your well, GAMA - Well Owners at State Water Resources Control Board is the official source.
Already have results? Get the lab report read line by line, $29.
Testing by county
The contaminant most often over its limit in each county's public record, highest share first. Open a county for the full test list and its towns.
Closer than the county: see the sampled wells near your address.
Free, no obligation
Get on the list for a free in-home water test in California
We are signing licensed water treatment companies county by county. They test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Nothing is shared until a company joins for your area, and you get an email naming it first.
Common questions
What should I test my well for in California?
Start with nitrate, arsenic, uranium. 16% of 57,577 local samples were above the limit. Add total coliform bacteria and nitrate every year for any private well.
Where can I get my well water tested in California?
Use a lab certified for drinking water. State Water Resources Control Board keeps the list of certified labs. A mail-in kit from a certified lab works anywhere in the state.
How much does well water testing cost in California?
A full mail-in panel from a certified lab costs $209 (Tap Score well water test kit). A bacteria-only test costs $99 (Tap Score coliform and E. coli test).
Is there free well water testing in California?
The State Water Resources Control Board and Regional Water Boards fund free domestic well testing programs across many parts of the state, each with its own service area and eligibility, listed in a county-by-county directory.
How often should a private well be tested?
Bacteria and nitrate every year. A full panel once, then again after flooding, a change in taste, smell or color, work on the well, a new baby in the house, or a nearby result above the limit. Contaminants that come from the rock, like arsenic, radon and uranium, change slowly, so one good test and a check every few years is enough.