Kyla Bennett, director of science policy for Public Employees for Environmental Responsibility in New England, urged Cambridge residents to stop using the city’s water because of the reported levels of PFAS.

Bennett lives in Easton, where the town is spending more than $9 million on a treatment plant to remove the chemicals.

She said she thinks drought conditions are a contributing factor to the increase in Cambridge’s PFAS levels. The conditions helped the chemicals become concentrated in the ground, and then they are flushed by rain into water supplies.