Rainwater Harvesting and PFAS Contamination
Rainwater harvesting is promoted as a sustainable water source for irrigation and non-potable uses, but recent research demonstrates that PFAS deposited from atmospheric sources contaminate even remote rainwater to concentrations exceeding EPA health advisories.
Atmospheric PFAS Deposition
PFAS enter the atmosphere from industrial emissions, firefighting activities, and degradation of fluorinated compounds. Wet deposition (rain) and dry deposition (dust) deliver PFAS globally, including to rainwater harvesting systems far from direct sources.
Health Implications for Potable Rainwater Use
Some jurisdictions permit potable rainwater harvesting, but without PFAS treatment, collected water may not meet MCLs. 2023 PFAS rainwater sampling studies in the US found PFOA and PFOS concentrations above EPA’s 4 ng/L limits in many locations.
Treatment Technologies for Rainwater
Granular activated carbon filtration downstream of first-flush diverters provides effective PFAS reduction in rainwater systems. Reverse osmosis achieves near-complete removal for potable applications. System design should include PFAS removal as a standard component in contaminated regions.