Pathogen Reduction Crediting for Reverse Osmosis: Getting Credit where Credit is Due with Good Surrogates

<jats:p>Key Takeaways Reverse osmosis (RO) is an excellent barrier against pathogens (e.g., 6-log10 virus reduction), but is under-credited for pathogen reduction due to the lack of good surrogates. Conductivity and total organic carbon, the most common surrogates, only provide log reduction credits of 1.5 to 2 log10. Other naturally occurring ions provide opportunity to increase RO credits up to 3-log10 . Alternative approaches—such as the use of spiked surrogates—have the potential to provide 4- or 5-log10, but more research is needed for implementation. This issue shows practitioners and regulators how to extend RO crediting with existing surrogates and points to the need for further research to maximize RO’s full potential.</jats:p>