The Orange County Water District and cities throughout the county have filed a joint lawsuit against 3M, DuPont, and other companies, claiming the defendants deliberately contaminated groundwater and water systems throughout the Southern California region. The plaintiffs—including the cities of Orange, Anaheim, Fullerton, Garden Grove, Santa Ana, and Tustin, along with the water districts of East Orange County, Irvine Ranch, Serrano, and Yorba Linda—allege that the companies contaminated the Orange County Groundwater Basin and the Santa Ana River with polyfluoroalkyl substances (PFAS). The water supply in question services more than 2.5 million people. PFAS are man-made chemicals that include PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctane acid), and are widely used in the manufacturing industry when producing many common household products. The chemicals are toxic to the environment and the human body, and can lead to adverse health effects in humans. The lawsuit, filed by SL Environmental Law Group in Orange …