A U.S. appeals court on Wednesday ruled that an environmental group can press ahead with claims that a toxic chemical in a central California city’s drinking-water system qualifies as “solid waste” under the federal Resource Conservation and Recovery Act.

Overturning a lower court ruling, a split panel of the 9th U.S. Circuit Court of Appeals found that the city of Vacaville can potentially be held liable under the RCRA for transporting in its water pipes the carcinogen hexavalent chromium, which an environmental group claims is the result of commercial pollution at a site where the city draws its water.