Last checked: October 22, 2026

Well pros and certified labs in Fresno County, CA

4 certified labs listed for Fresno County on official California license and certification lists. The full statewide list, how California licenses contractors, and how to check a license yourself are on the California directory page.

The list for Fresno County

Not seeing anyone? Many businesses serve several counties. Check the full California list, which you can filter by county.

Questions to ask before hiring a well contractor

Get information on several contractors before you choose.¹ These questions come from the National Ground Water Association's well owner guidance and New York DEC's consumer checklist:¹²

• Are you licensed, registered or certified by the state for this work? Not every state requires it. Check the answer yourself with the state lookup on this page.
• Is the person supervising the job certified? NGWA offers voluntary certification; its highest level is Master Groundwater Contractor (MGWC).¹
• Do you file a well log or completion report, and will I get a copy? Some states require the driller to give the owner a copy (New York does, for example).² Keep it with your deed.¹
• What liability and workers' compensation insurance do you carry?¹
• Can I talk to recent customers? Ask for references and call them.²
• Will you give me a written contract?¹ In New York, for example, home improvement work over $500 needs a written contract by law.²
• Do I need a local permit? Check with your local health and building code officials. Some counties set their own rules.²

What to check on a quote

Get more than one estimate.² NGWA says an itemized list of charges is better than a lump sum, because you can't compare offers unless you know what each one covers.¹ For a drilled well, look for:¹

• Price per foot of drilling and per foot of casing, plus the casing diameter and thickness
• Other materials (drive shoe, grout, well cap) and other steps (grouting, development, test pumping, disinfection)
• The type of well cap or seal, and the disinfection procedure
• What happens, and what it costs, if they must drill deeper or drill a second well, or abandon and seal a dry or bad hole
• Cleanup of the site, an expected start date, and a guarantee of materials and workmanship
• A statement that the work will meet state and local codes
• What is not included

When the well is finished, NGWA suggests checking the depth against the construction report, asking what yield (gallons per minute) the well was tested at, making sure the cap is secure and at least 6 inches above ground, asking whether the well was disinfected, and getting your copy of the well record.¹

Buying treatment? Test first. A lab report from a state-certified lab tells you what you're actually treating for. Pennsylvania DEP, for example, says to pick a treatment device for the specific contaminant your test found, and points to NSF's product database.³ Put your numbers into our free Well Test Results Checker to see how they compare with EPA benchmarks.

More for Fresno County well owners

• Well water testing in Fresno County: local test data, labs and contacts
• California directory and how to verify a license
• Well Test Results Checker (free, runs in your browser)