From the State Water Board:
On June 17, 2021, the Office of Administrative Law approved the perchlorate detection limit for purposes of reporting (DLR) regulations adopted by the State Water Board on October 6, 2020. The regulations will take effect on July 1, 2021.
The DLR will change from 0.004 mg/l to 0.002 mg/l on 1 July 2021, and further decrease to 0.001 mg/l on 1 January 2024.
Water systems with questions regarding the revised DLR should contact their local Division of Drinking Water District Office or Local Primacy Agency.
Additional information on the regulation of perchlorate in drinking water can be found by visiting https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/Perchlorate.html. A summary of the rulemaking status and the complete rulemaking file are available at https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/perchlorate2.html.
