As water-stressed regions increasingly adopt reclaimed water (treated wastewater) for non-potable and indirect potable reuse applications, PFAS in wastewater treatment plant (WWTP) influent raises important questions about PFAS occurrence in reclaimed water and the appropriate treatment to address it.
PFAS in Wastewater Treatment Plant Influent
Household and commercial PFAS use — from consumer products, cleaning agents, and other sources — enters wastewater collection systems and reaches WWTPs. Conventional biological treatment processes do not remove PFAS and may actually increase PFAS concentrations in some cases by transforming PFAS precursors to perfluoroalkyl acids. WWTP effluent consistently contains PFAS, making surface water bodies receiving WWTP discharge potential PFAS sources for downstream drinking water intakes.
Reclaimed Water Applications
Non-potable reclaimed water used for landscape irrigation, industrial cooling, and toilet flushing generally has less stringent PFAS treatment requirements than potable applications. However, as reclaimed water use expands to indirect potable reuse (introducing reclaimed water to a drinking water reservoir or aquifer) and direct potable reuse, PFAS treatment to drinking water standards is required. Advanced treatment trains for potable reuse typically include microfiltration, RO, UV, and advanced oxidation — a sequence that effectively addresses PFAS alongside other contaminants.
Consumer Implications
Consumers in regions with established water reuse programs should understand the treatment levels applied to reclaimed water in their area. State-regulated indirect potable reuse programs require treatment to drinking water standards, providing PFAS protection equivalent to conventional treatment. Direct tap water customers in areas where reclaimed water is blended into supply should verify that PFAS monitoring includes testing of the reclaimed water component specifically.