Private well owner checklist

Who this is for

Homeowners and renters who use a private well, and anyone who helps them. The full explanation is in Private wells and nitrate: testing, health risks and California help.

How to use it

1. Print this page and keep it with your well records.
2. Work through Parts 1 to 3 before you test, and Parts 4 to 6 when the result comes back.
3. Write each year's result in the test record at the end, so you can see whether nitrate is rising.

This page is for your own use; keep your completed copy private. It records information. It does not replace advice from your clinician, your county environmental health office or a licensed well contractor.

Part 1: Before you test

• Check for a free program first (Central Valley). Look up your address on the CV-SALTS Find Your Management Zone map. If you or your landlord pays a monthly water bill, you are likely on a public system and not covered.
• Check the state's program directory (California). The State Water Board's AB 2454 page links a county-by-county list of state-funded well testing programs.
• If you rent (California): ask your landlord whether a free state-funded testing program covers the property. If one does, the landlord must test through it and share results within 10 days.
• If paying for a test: choose a laboratory accredited by the State Water Board's Environmental Laboratory Accreditation Program (ELAP), and ask for a written estimate.
• Test now, not later, if someone in the home is pregnant or nursing, a baby or young child lives with you, the well flooded, or there has been construction or another big change near the well.

Part 2: Questions for the lab

• "Can you test for nitrate and nitrite, and report nitrate as nitrogen (N)?"
• "Can you also test for total coliform bacteria and electrical conductivity?"
• "What other contaminants are common near me?" (In much of Fresno, Tulare, Kings and Kern counties, these can include arsenic, uranium, DBCP and 1,2,3-TCP.)
• "Will you send clean sample bottles and written instructions?"
• "How should I store the sample, and how soon must it reach you?"
• "What will the full package cost?"

Part 3: Taking the sample

• Use only the bottles the lab provides.
• Sample as close to the well as you can, from a spigot near the wellhead if there is one.
• Sample before any filter, softener or other treatment device.
• Follow the lab's storage and return instructions exactly.
• Write down the date, time and tap used.

Part 4: Reading the result

Find the nitrate line and check its units first.

• Below the limit: keep testing at least once a year.
• At or above the limit: go to Part 5, and ask for a re-test to confirm.
• Bacteria found: ask the lab or your county environmental health office what to do; this needs its own fix.

Part 5: If nitrate is at or above the limit

• Stop using the water for drinking, cooking, ice and baby formula.
• Do not boil the water. Boiling does not remove nitrate and can concentrate it.
• Use bottled or other safe water, first for babies and anyone pregnant.
• Keep bathing, showering, handwashing and laundry as usual; nitrate is not absorbed through the skin.
• If you are pregnant or care for a baby, tell your clinician or the baby's clinician about the result.
• Ask your management zone or another free program about bottled water delivery.
• Ask your county environmental health office or a licensed well contractor about longer-term fixes.

Part 6: Choosing treatment

• Type: reverse osmosis or anion exchange. A pitcher, faucet or refrigerator filter, or an ordinary water softener, will not remove nitrate unless its certification lists nitrate.
• Certification: for reverse osmosis, look for NSF/ANSI 58 with a nitrate/nitrite reduction claim.
• California registration: look the device up on the State Water Board's list of registered devices, and read its Performance Data Sheet.
• Fit: confirm your nitrate is no higher than 24 mg/L as N (108 as NO3) and your water pressure is at least 40 psi, the conditions the State Water Board gives for home nitrate treatment.
• Upkeep: replace filter parts on the maker's schedule, and have the treated water lab-checked regularly.

Part 7: Yearly well care

The State Water Board suggests these routine checks:

• Look over the well each year for damage, cleanliness and mechanical problems.
• Keep fuel, motor oil, pesticides, fertilizer and paint well away from the well.
• Keep the wellhead at least one foot above the ground, with the cap intact, and make sure water drains away from it.
• Do not let surface water pool around the well.
• If the well is 20 years old or more, have a licensed well driller or pump installer inspect it.

Test record

Contacts

Central Valley numbers, as of October 2026: Kings Water Alliance, (559) 549-6747. Self-Help Enterprises water quality team, 559-802-1285; bottled water, 559-802-1284.

Limitations

This checklist summarizes public guidance from state and federal agencies and a certifying body as of October 2026. It is not a test, a diagnosis or a product endorsement. Program areas, eligibility and services change, so confirm them with each program. Costs, contaminants of concern and well rules vary by county.

Sources

1. Nitrates and Nitrites in Drinking Water and Nitrate Fact Sheet — California State Water Resources Control Board; fact sheet by the California Department of Public Health, May 2014.
2. A Guide for Private Domestic Well Owners and GAMA – Domestic Well Testing — State Water Resources Control Board, June 2025 and September 15, 2023.
3. Protect Your Home's Water — U.S. Environmental Protection Agency, last updated February 26, 2026.
4. Residential Water Treatment Devices — State Water Resources Control Board, page last updated June 27, 2025.
5. NSF/ANSI 58: Reverse Osmosis Drinking Water Treatment Systems and certified drinking water treatment unit listings — NSF, accessed October 26, 2026.
6. Rental Property Domestic Well Testing Requirements (AB 2454) — State Water Resources Control Board, accessed October 26, 2026.
7. Find Your Management Zone — CV-SALTS, accessed October 26, 2026.
8. Free Well Testing & Bottled Water Delivery: How to Get Started — Kings Water Alliance; Water Quality and Safe Drinking Water — Self-Help Enterprises; accessed October 26, 2026.