PFAS in Recycled Water Systems
Water recycling — treating municipal wastewater for reuse in irrigation, industrial processes, and increasingly as potable water — is growing as water scarcity intensifies globally. However, PFAS pass through conventional wastewater treatment essentially unchanged, meaning recycled water carries the PFAS load of its source wastewater. This creates PFAS exposure risks when recycled water is used for food crop irrigation or potable reuse.
Studies of recycled water used for agricultural irrigation have found PFAS uptake into crops, with leafy vegetables and strawberries showing the highest bioconcentration. PFAS applied through irrigation water accumulates in soil over time, creating legacy contamination that persists even after irrigation practice changes.
Treatment Technologies for PFAS in Water Reuse
Advanced water purification systems used in direct potable reuse — microfiltration, reverse osmosis, UV/advanced oxidation, and disinfection (the ‘triple barrier’ approach) — effectively remove PFAS. RO is the critical barrier for PFAS, achieving >99% removal. Systems designed to the Orange County Water District’s Groundwater Replenishment System standard provide PFAS concentrations well below current MCLs.
For non-potable reuse applications where full RO treatment is not cost-justified, granular activated carbon treatment can reduce PFAS to acceptable levels for many applications. The appropriate treatment level depends on the intended use — irrigation of food crops warrants stricter treatment than industrial cooling water.
Regulatory Considerations for Recycled Water
States regulating water recycling are updating requirements to address PFAS. California’s Title 22 recycled water standards are being revised to incorporate PFAS monitoring and treatment requirements consistent with the state’s drinking water standards. Other states with active water recycling programs are similarly updating frameworks.
International examples — including Singapore’s NEWater, which provides approximately 40% of the nation’s water needs through advanced water reclamation — demonstrate that PFAS can be effectively managed in potable reuse with appropriate treatment. Singapore’s multi-barrier approach and rigorous monitoring provide a model for PFAS management in water reuse systems.