Water testing in California

Kings Water Alliance Free Well Testing and Bottled Water Delivery

Free

• Nitrate

Check your address on the interactive service area map, then complete the Residential Drinking Water Well Survey online or by mail to request a free well test.

Must live within the Kings Water Alliance service area and rely on a private well for drinking water; check the interactive map and complete the Residential Drinking Water Well Survey to confirm eligibility.

• Kings Water Alliance / Kings River Water Quality Coalition, P.O. Box 8259, Fresno · 559-549-6747

Checked October 1, 2026. Report a change

Free Well Testing via Valley Water Collaborative

Free

Apply online at valleywaterc.org or call (209) 750-3867 to request free well water testing.

Subject to grant funding availability; applicant must qualify (specific qualification criteria not stated on the flyer).

Checked October 1, 2026. Report a change

Butte County Public Health Laboratory Water Testing

$28

Water sample testing at BCPHL costs $28.

• Bacteria
• Fecal coliform
• E. coli

Pick up sterile water collection bottles from BCPHL or the Environmental Health Division, collect your well water sample following the posted procedure, and deliver it to the Butte County Public Health Laboratory with the completed water submittal form and $28 fee.

• Butte County Public Health Laboratory, 695 Oleander Avenue, Chico · 530-891-2747
• Butte County Environmental Health Division, 202 Mira Loma Drive, Oroville · 530-552-3880

Checked October 1, 2026. Report a change

Napa-Solano-Yolo-Marin Public Health Laboratory Water Testing

$38

• Bacteria
• E. coli
• Nitrate

Pick up a sample collection bottle from one of the lab's drop-off locations in Napa, Solano, Yolo, or Marin County, collect your water sample, fill out the Water Testing Requisition form, and drop off the sample with payment by Thursday.

• Napa-Solano-Yolo-Marin Public Health Laboratory (main lab), 2201 Courage Dr, Fairfield · 707-784-4410
• Napa County Health and Human Services - Public Health (drop-off), 2751 Napa Valley Corporate Drive, Napa · (707) 253-4270
• Yolo County Environmental Health (drop-off), 292 W. Beamer St, Woodland · 530-666-8646
• Marin Health and Wellness Campus (drop-off), 3240 Kerner Boulevard, San Rafael · 415-473-4163

Checked October 1, 2026. Report a change

Sonoma County Public Health Regional Laboratory Well Water Testing

$39

• Bacteria
• E. coli

Pick up an approved sample bottle and requisition form at 3313 Chanate Road in Santa Rosa, collect the sample, and drop it off Monday through Thursday, 8 a.m. to 4 p.m.

Open to the public; only water collected in a bottle provided by the lab will be tested; the lab does not test for chemicals, metals, minerals, or Giardia.

• Public Health Regional Laboratory, 3313 Chanate Road, Santa Rosa · 707-565-4711

Checked October 1, 2026. Report a change

San Luis Obispo County Public Health Laboratory Water Testing

$52

• Bacteria
• E. coli

Pick up a sterile sample bottle at a Public Health Department location, collect a water sample following the lab's instructions, and drop it off with the completed requisition form and payment at the San Luis Obispo or Paso Robles Public Health Department.

• San Luis Obispo County Public Health Laboratory, 2191 Johnson Avenue, San Luis Obispo · (805) 781-5507
• Paso Robles Health Dept. (sample drop-off), 805 4th Street, Suite #201, Paso Robles · (805) 237-3050

Checked October 1, 2026. Report a change