Pathogen Removal Credits for Wastewater Reuse: Guidance for Study Plans and Reporting

The current regulatory framework for potable reuse relies on the ability to grant treatment credits for the reduction of pathogens from wastewater by secondary, tertiary, and advanced treatment processes. In the past, secondary and tertiary treatment facilities sought credits based on historical pathogen datasets. However, the performance of treatment processes is highly variable and depends on many design, operational, and environmental factors. Thus, regulators are recommending site-specific studies.

The objective of this project was to provide guidance on the development and implementation of study plans to validate pathogen log10 reduction values (LRVs) to assign credits for secondary and tertiary wastewater treatment processes in water reuse systems. The research team used systematic literature review, consultation with industry experts, meta-analysis, and in-silico analysis, to produce key findings and recommendations. Research partner: California State Water Resources Control Board. Published in 2023.