California Water Views

On August 6, 2024, the Office of Administrative Law (OAL) approved the direct potable reuse (DPR) regulations that were previously adopted by the State Water Resources Control Board (State Water Board) on December 19, 2023. The approved regulations – which go into effect on October 1, 2024 – will allow public water systems and other agencies in California to obtain permits to develop DPR projects.

DPR is when purified recycled water is placed directly into a public water system or into a “raw” (untreated) water supply immediately upstream of a drinking water treatment plant. The extensive DPR regulations require an exceptionally high level of treatment, reflecting the recommendations of independent expert review panels and advisory groups convened by the State Water Board to ensure the DPR regulations will protect public health.

Public water systems and other agencies that choose to develop a DPR project must comply with the DPR regulations. Before moving forward with DPR, a public water system is required to hold at least one public meeting, provide notice to customers of the public meeting, and make information available to customers regarding how the public water system plans to engage in DPR. A public water system engaging in DPR must also provide information in the annual consumer confidence report about the DPR project.

As there are currently no public water systems in California permitted to operate a DPR project, the construction and operational costs associated with such projects are largely unknown and the State Water Board indicated in a recent FAQ document that “cost estimates are still being developed.” While higher treatment costs are required to purify DPR water to required standards, these costs may not be as high as costs to implement indirect potable reuse which requires treatment, injection and filtration time in aquifers or water supply surface storage, retrieval and retreatment.

More information on the historical background on DPR in California and the State Water Board’s adoption of the DPR regulations last December can be found in our previous blog post on this topic.