History was made at the end of last year when California, USA passed regulations allowing ‘direct potable reuse’.

DPR means purified recycled water provided directly into drinking water pipes and distribution systems for the community, without first spending time in an environmental buffer such as an aquifer or reservoir. The purified recycled water could be added before the conventional water treatment plant, or afterwards directly into the distribution system. 

The news received coverage across the US, plus in Australia and the UK. Predictably, some of the media coverage used sensationalist headlines like ‘toilet to tap’ or ‘turning sewage into drinking water’, though the coverage was mainly factual and pointed to the growing need to build drought-proof water supply options for the 39 million people of California.

Though the story made headlines, direct potable reuse is not new in America – Colorado already has its own regulatory framework, and Texas allows it, with schemes operating today in Big Spring, and Wichita Falls for several years, and El Paso building a DPR facility for the future. Utah and Arizona also have such regulations in development. Beyond the US, the city of Windhoek, Namibia, has been providing safe and reliable water to its residents through DPR since 1968; Beaufort West since 2011. Cape Town recently announced new projects being developed for the future.


The California DPR framework was the result of well over a decade of collaboration and advocacy from the US water industry.

“WateReuse California commends the State Water Board on adopting regulations that protect public health while providing a vital new tool for California’s sustainable water future,” said David Pedersen, General Manager of the Las Virgenes Municipal Water District and President of WateReuse California. “WateReuse California has collaborated with the Water Board and countless stakeholders for over a decade to reach this important milestone.”

“Today heralds a new era of water reuse, making it possible for more communities across California to benefit from an abundant, safe, resilient, and local water supply, and serving as an example to other states” said Patricia Sinicropi, Executive Director of the WateReuse Association.

Indirect potable reuse or IPR (which means purified recycled water which spends time in environmental buffer such as a reservoir, before being distributed to homes, schools and businesses) has been in use for decades in California – one of the earliest projects was the Montebello Forebay in 1962. Today there are nearly 40 projects in California alone either already providing purified recycled water to their communities, or in the planning stages (see maps courtesy of US WateReuse Association). Some use groundwater, like Orange County (490 megalitres/day); others will use surface water (Pure Water San Diego will provide nearly half the water supply for San Diego by 2035).

DPR is something we are likely to hear more of, with the Pure Water Southern California project alone planning to provide water to 19 million people through a combination of IPR and DPR. As the experts say, it’s all just water – whether direct or indirect. As the world looks on, the California news is a great leap forward towards sustainable water use around the globe.

For more detail about the California DPR framework visit https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/dpr-regs.html


1 Feb 2024

Danielle Francis

Danielle Francis