The City of Portsmouth’s water system tests for Poly- and Per- Fluoro Alkyl Substances (PFAS) in all of our sources of supply quarterly. Four PFAS chemicals are regulated by the NH Code of Administrative Rules, Chapter Env-Dw 700. These rules establish Maximum Contaminant Levels (MCLs), and compliance requirements for: PFOA, PFOS, PFHxS and PFNA. Currently all of Portsmouth Water’s sources are in compliance with the New Hampshire MCLs.