Rural Water Independence and PFAS Risk
Cisterns and rainwater collection systems provide water independence for rural households not served by municipal systems. However, atmospheric PFAS deposition means collected rainwater may contain PFAS at concentrations that can pose health risks without treatment.
PFAS in Cistern Water: Testing Evidence
Studies of cistern water in rural communities show PFAS detection at concentrations ranging from below detection to multiple times EPA health advisory levels, depending on proximity to industrial sources and atmospheric deposition rates. PFAS in roof runoff reflect both atmospheric deposition and leaching from roofing materials.
Roofing Materials as PFAS Sources
Certain roofing materials including some metal roofing coatings and composite shingles can leach PFAS into collected rainwater. First-flush diverters that discard the initial rainfall—which carries the highest contamination from surface buildup—reduce but do not eliminate PFAS in cistern water.
Treatment for Potable Cistern Use
Cistern systems used for drinking water should incorporate GAC or RO treatment downstream of first-flush diversion and particulate filtration. Annual PFAS testing of treated cistern water confirms ongoing system performance and guides maintenance scheduling.