dhs-ehs-banner-500x100.jpg

Water Testing

Although your well water may taste and smell fine, the only way to know your well water is safe is by testing it. Harmful bacteria or chemicals that you cannot see, smell or taste could be present.

A laboratory certified for bacteriological and/or chemical analysis can perform tests on your well water to determine its water quality.

Laboratories Certified for Bacteriological and/or Chemical Analysis

Brelje and Race Laboratories, Inc.
425 South E Street
Santa Rosa, CA 95404
Telephone (707) 544-8807
(bacteriological and chemical testing)

Sonoma County Public Health Regional Laboratory
3313 Chanate Road
Santa Rosa, CA 95404
Telephone (707) 565-4711
(bacteriological testing)

Caltest Analytical Laboratory
1885 North Kelly Road
Napa, CA 94558
Telephone (707) 258-4000
(bacteriological and chemical testing)

Far West Laboratories Inc.
P O Box 355
Riverbank, CA 95367
Telephone (800) 750-9260
(209) 869-9260
(bacteriological and chemical testing)

Disclaimer: The Sonoma County Department of Health Services makes no assumption of quality and makes no warranties regarding providers appearing in this resource guide. This resource guide simply a public listing provided for consumer convenience, and is not a recommendation or endorsement by the Department.

Water Quality Tests

There are many tests that can be performed on your well water to determine its water quality. This is a list of the most commonly performed tests and their recommended testing frequencies.

Because bacteria and nitrate are the most common contaminants of well water, they should be tested most frequently. The minerals test is recommended for the purposes of developing a baseline understanding of your water and as a way to indicate water quality changes.

Bacteria

Test type: EPA Colilert Method, Total Coliform and Fecal Coliform
Frequency: twice a year

If the lab report shows the presence of total coliform bacteria look for the cause, eliminate it if possible, and continue to test the water at an increased frequency. You may consider installing a treatment system such as distillation, chemical disinfection or ultraviolet radiation. Consult a water treatment professional for more advice.

Nitrates

Test type: EPA Method 200 series
Frequency: every five years

If >45 mg/I N03 or >1Omg/I N03-N, install a treatment device or find an alternative water supply. Increase the testing frequency. Filtration using reverse osmosis will remove some of the nitrate. Consult a water treatment professional for more advice.

Minerals

Test type: EPA Method 200 series
Frequency: every 5 years, or if a change in the water taste or color is detected

Most water testing companies offer a group minerals test for all listed minerals. Be sure to compare the results with previous results.

The levels listed below are set by the State of California CCR Standards for Drinking Water. If mineral levels are greater than or equal to these levels, you should install a treatment system or determine an alternative supply of water. An appropriate treatment system is dependent on the minerals to be removed.Consult a water treatment professional for more advice.

Aluminum(AI), 1.0 mg/I
Arsenic (As)0.05 mg/I
Barium (Ba), 1.0 mg/I
Cadmium (Cd), 0.005 mg/I
Chromium (Cr) 0.05 mg/I
Fluoride(F), 2.0 mg/I
Iron (Fe), 0.3 mg/I
Lead (Pb),.015 mg/I
Manganese (Mn), 0.05 mg/I
Mercury (Hg), 0.002 mg/I
Selenium (Se), 0.05 mg/I
Silver (Ag) 0.1 mg/I

Petroleum

Test type: Petroleum hydrocarbons by EPA Method 8015 and BTEXIMT BE by EPA Method 8260
Frequency: every three to five years

There is no drinking water standard for petroleum hydrocarbons. If petroleum hydrocarbons are suspected or detected at all, then the well also should be tested for benzene, toluene, ethylbenzene, and xylenes (BTEX) and methyl tert-butyl ether (MTBE), which do have standards. If petroleum hydrocarbons, BTEX or MTBE are detected then a treatment device can be used or the homeowner may seek an alternative water supply. Consult a water treatment professional for more advice.

Solventery

Test type: Organic Compounds (solvents) by EPA Method 8260
Frequency: every three to five years

Each solvent has a specific drinking water standard. If solvents are detected then a treatment device can be used or the homeowner may seek an alternative water supply. Consult a water treatment professional for more advice.

Pesticides

Test type: Orqanichlorine Pesticides by EPA Method 8080, Herbicides by EPA Method 8150
Frequency: every three to five years

Each pesticide has a specific drinking water standard. If pesticides are detected then a treatment device can be used or the homeowner may seek an alternative water supply. Consult a water treatment professional for more advice.

Contact Information

Public Health Division
County of Sonoma
Business Hours
Monday – Friday
7:30 AM – 4:30 PM
Address
Office Location
625 5th Street
Santa Rosa, CA 95404
38.44178, -122.7158781

Report a Complaint, Hazard or Nuisance

Public Records Requests

Public Records Requests
Most Environmental Health records are available electronically and you may search our database via the Public Access Viewer.