On December 14, 2017, California’s State Water Resources Control Board adopted a new Maximum Contaminant Level (MCL) for 1,2,3-Trichloropropane (TCP) of 5 parts per trillion (ppt) and established that all water providers must begin testing their sources for the contaminant by January 2018.

Golden State Water would like to assure customers that we routinely monitor and test for more than 230 contaminants, including TCP, to ensure the water we deliver to customers meets all state and federal drinking water standards. Golden State Water makes water quality information available via annual Consumer Confidence Reports (CCR).

As your water provider, we continually invest in water infrastructure, treatment and testing and take great pride in providing you with high quality, reliable water. We will work to ensure that all of our water supplies comply with the new TCP MCL and water serving your system will continue to meet all federal and state water quality standards.

Frequently Asked Questions

Q:  What is TCP and where does it come from?
A:  TCP is a manmade chemical, a chlorinated hydrocarbon, found at industrial or hazardous waste sites. It was used as a cleaning and degreasing solvent and is associated with pesticide products, such as soil fumigants. TCP causes cancer in laboratory animals and has been classified by the USEPA as likely to be a human carcinogen.

Q:  Has TCP been found in my drinking water?
A:  In 2017, TCP was detected in drinking water in only one of Golden State Water’s 38 water systems. The well in which TCP was detected (at levels of 5.3 to 5.9 ppt) is in the Claremont system and was taken out of service until treatment is installed.

Q:   How is TCP removed from contaminated water sources?
A:  TCP can be effectively removed using granular-activated (GAC) technology. GAC vessels installed at impacted wells eliminate or substantially reduce the levels of TCP to below the new MCL.

Resources for Additional Information

State Water Resources Control Board

United States Environmental Protection Agency