Community Water Center

Community-driven water solutions through organizing, education, and advocacy

Pilot Program Provides Insight into Private Well Water Quality


By Vanessa Martinez 

Community Water Center recently completed a year-long pilot private well testing project in May. This free water testing program was designed to inform local residents of their water quality. We tested a total of 32 private wells in the Central Valley. Based on the results, residents could then make their own informed decisions regarding their drinking water needs. In addition to providing residents their water quality results, resources about how to obtain safe drinking water were also provided. Residents decided whether or not to continue using the water for drinking, cooking, or irrigation needs.  

In order to properly complete the water sampling, CWC team members Jerry Tinoco and Heather Luckas completed a certification course at BSK Labs in Fresno, who later trained Erasto Teran. The three CWC staff collected water samples from domestic private wells located in the communities of Alameda, East Porterville, Exeter, Monson, Orosi, Porterville, Reedley, Terra Bella, Visalia, and Yettem. Water samples were tested in a Bakersfield laboratory for seven priority contaminants: total coliform, E. Coli, nitrate, 1,2,3-TCP, DBCP, arsenic, uranium, and hexavalent chromium.

The lab testing provided the following results:

Exceedances by contaminant for 32 Wells Sampled:

Nitrate: 9 wells over the MCL (plus one test very close to the MCL).

Coliform: 14 wells with positive results.

E.Coli: 3 wells with positive results.

Arsenic: 1 well over the MCL (plus 28 above the PHG).

1,2,3-TCP: 2 above the notification limit, 3 total above the PHG.

Uranium: 31 over the PHG, none over the MCL.

Hexavalent Chromium: 26 over the PHG, none over the MCL.

As the above numbers indicate, many wells tested were found to have drinking water contamination levels above legal levels or Maximum Contaminant Levels (MCL). Surprisingly, out of the 32 wells tested, about 26 wells had never been tested for water contamination before. CWC staff provided residents with fact sheets, letters of results, drought relief information, and other educational materials to help inform them of drinking water impacts and resources. This graph below shows the percentage of wells tested that contained at least one of the 7 contaminants with respect to MCL/NL (notification level) and PHG (public health goal).


While our testing revealed unfortunate results of disproportionate water contamination in Central Valley private wells, there were many positive outcomes of the project. Most importantly, residents learned about their water quality and are now able to make decisions about their water needs. Furthermore, the data collected can serve as an example and resource for other organizations. The data from this project was entered into the State Water Board’s Geotracker GAMA website for public use. A similar well sampling project is underway for East Porterville. We hope to continue and expand this program in the future, and that the results of our initial round of testing can be on a larger scale to other locations.

For more information regarding CWC’s private well testing visit our Private Well Testing Page.

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