Earlier this month the California Sate Water Resources Control Board released a report on the feasibility of direct potable reuse (DPR). The report, drafted by a 12-member panel of global experts on the issues surrounding DPR, concludes that it is possible to regulate DPR in a way that enables the production of safe and reliable drinking water from purified and recycled sewage.
DPR is defined by the California Water Board as “The delivery of purified water to a drinking water plant or a drinking water distribution system without an environmental buffer. ”
Other states such as Texas and New Mexico have accepted DPR on a case-by-case basis. By regulating direct potable wastewater recycling, California will become the first state to embrace it as a new drinking water supply.
It’s important to note that the existing water reuse facilities in the state of California—in Orange County, Santa Clara, and San Diego—are considered indirect potable reuse facilities because they include an environmental buffer in their treatment processes. These facilities purify water to drinking water standards by way of microfiltration, reverse osmosis, and ultraviolet light, and then pump it into settling basins where it can trickle down through gravel and sand and recharge groundwater aquifers or blend it with non-recycled water in a reservoir or aquifer. Direct potable reuse would eliminate the environmental buffer and make water immediately available for distribution.
The report indicates that an additional engineered process will be needed to substitute for the environmental buffer although the state has not yet determined what that process will be. In addition, the committee has asked the California State Water Control Board to consider six different areas requiring further research.
One area requiring in-depth investigation is the topic of contaminants such as pharmaceuticals and chemicals that are not eliminated by traditional wastewater treatment processes. In the coming months, the state water board will need to determine which chemicals it will regulate and what processes will be incorporated to control them in coming months.
Randy Barnard, recycled water unit chief at the state water board, told Water Deeply that the agency will begin to draft those regulations, based on the encouraging findings of the experts. “There are agencies all up and down California that would consider a project like this. There’s a lot of interest,” Barnard said. “But they’re just waiting on what the requirements are going to be and what they have to do to move forward.”
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