CalVal Phase 1 Technical Survey: Evaluating Treatment Credits and Compliance Pathways for Indirect Potable Reuse in California

This project addressed critical challenges in the field of water recycling, particularly Indirect Potable Reuse (IPR) in the state of California. IPR involves enhancing surface water or groundwater with highly treated wastewater to meet drinking water standards, offering a sustainable solution to water supply issues. However, the lack of uniform regulatory criteria for treatment technology validation presents significant challenges to utilities and project developers. These challenges include knowledge gaps, regulatory uncertainties, and increased project costs.

This project worked to establish a systematic and reliable scientific approach to assess the efficacy of IPR treatment processes currently in use. The research team created a comprehensive guidance document rooted in widely accepted scientific methods and practices that prioritizes public health and increase the availability of clean water sources in the United States. This guidance will involve using top-notch scientific methods to confirm treatment credits achieved in the IPR and will set and promote best practices in treatment performance validation in the context of potable reuse.

The overall goal of this project is to empower utilities, regulators, ratepayers, and other stakeholders nationwide to make well-informed and transparent comparisons when considering advanced water treatment investments. This project was awarded through WRF's Tailored Collaboration Program, and the cost-share comes from WateReuse California, with LADWP as the supporting organization. Published in 2025.