California Water

Private Wells

When water is provided by a private well, periodic testing of its water is recommended but not mandated. Owners of private wells should use only laboratories certified by the California Department of Heath Services to conduct an analysis. Private wells fall outside federal and state regulation because they are on private land and not covered by the SDWA. They also are not subject to the same periodic testing and monitoring requirements as public water systems. There are more than 600,000 private wells in California.

Experts recommend having private well water tested at least once a year for coliform bacteria.

Experts recommend having private well water tested at least once a year for coliform bacteria. Shallow wells along rivers and wells built without proper sanitary seals are especially susceptible to bacterial contamination from surface water entry.

When it comes to toxic substances, more detailed - and expensive - testing can be done. Testing for minerals can cost from $130 to $200. Testing for organic "priority pollutants" may cost an additional $200 to $300. Testing for all regulated chemicals require even more extensive tests and can cost several thousand dollars per sample. If a contaminant is detected, the results will include the concentration of the contaminant and an indication of whether this concentration exceeds a drinking water quality standard. If a standard is exceeded, consumers are advised to retest the water supply immediately and contact the public health department for assistance.

Sometimes it is not necessary to check for the full range of pollutants. The health department probably is aware of metals or other possible contaminants of concern in the vicinity. County and state health departments keep records on well trouble spots and can advise whether any substances of concern have been found in other area wells nearby. However, water experts caution that different wells may not be drilled to the same depth or obtain water from the same geologic formation.

Information on well water quality may also be available from the State Water Resources Control Board. Included in the agency's Groundwater Ambient Monitoring and Assessment (GAMA) Program, is the Voluntary Domestic Well Assessment Project. The Voluntary Domestic Well Assessment Project samples domestic water wells for various chemicals commonly found in domestic well water and provides that information to the domestic well owners. As resources permit, the Voluntary Domestic Well Assessment Project focuses on specific areas of the state. The focus areas are chosen based upon existing knowledge of water quality and land use, in coordination with local environmental agencies. The state incurs the costs of sampling and analysis, and the results are provided to domestic well owners as quickly as possible. More information about the program is available at this website, http://www.waterboards.ca.gov/water_issues/programs/gama/voluntary.shtml

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