New Drinking Water Monitoring Requirements

Drinking Water Limits for 1,2,3 Trichloropropane (TCP)

Over the past several years the division of drinking water has received input from affected water systems, local community groups, and environmental justice groups expressing concerns about the need for drinking water standards for 1,2,3 Trichloropropane (TCP). On December 14, 2017, the California Office of Administrative Law officially approved a new maximum contaminant level (MCL) for TCP of 0.000005 milligrams per liter (five parts per trillion). Monitoring for TCP in drinking water systems is now mandatory starting in the first quarter 2018. Up until this formal adoption, the monitoring of drinking water wells for TCP were largely voluntary, yet TCP had been detected in drinking water systems in several counties across the state.​

Historically, TCP was used as a paint and varnish remover, a cleaning and degreasing agent, a cleaning and manufacturing solvent, and was a common component of soil fumigants previously used widely in agriculture. It’s also a waste product from making plastic. TCP is characteristically mobile in the subsurface, persistent, and resistant to natural attenuation. Given its low action level (5 parts per trillion), even very small amounts of TCP that reach groundwater can result in significant groundwater contamination.

TCP contamination of drinking water has been the subject of several large lawsuits which included the City of Clovis vs. Shell Oil. Shell Oil was the manufacturer of a soil fumigants which contained TCP. In December of 2016, the Courts found that Shell Oil was liable for the contamination of the city’s water wells and were required to pay 22 million dollars to the City of Clovis to treat the drinking water with granular activated carbon. This is the first time a community has won a lawsuit against a chemical company for TCP contamination and the flood gates have opened for additional lawsuits and settlements.

Now that drinking water systems will be required to test for TCP, more TCP contaminated groundwater will be identified. As there has been a successful law suit and a precedence is in place, drinking water providers will be searching for the responsible parties to pay for the drinking water treatment systems.  Manufacturers and those who want to avoid large lawsuits, will want to obtain environmental data to demonstrate that they are not responsible. Alta expects that over the next few years TCP contamination will become a central issue in the investigation and treatment of common contaminants in drinking water.

If you have questions or need advice, contact us at (888) 608-3010. ​