California regulators adopt wastewater reuse rules, knocking ‘toilet-to-tap’ misnomer

California regulators granted their unanimous support Tuesday for a long-awaited slate of rules that could flush future drinking water sources down toilets across the Golden State.

The California State Water Resources Control Board voted to approve regulations that would streamline “direct potable reuse” (DPR) — a method by which purified wastewater is released right into a public water system or just upstream from a treatment plant.

“If I had a balloon drop, you would see it dropping right now, and some confetti,” Joaquin Esquivel, chair of the State Board, said at the end of the Tuesday vote.

Esquivel and his colleagues also directed staff members to report back in a year with updates about any evolving science and technologies that could impact the implementation of these rules.

Although DPR earned the viral misnomer “toilet-to-tap” years ago, water used in the process won’t really be flowing directly from a toilet into a tap.

“We’ve been working on these regulations for over 10 years now, making sure that it’s absolutely protective of public health,” Darrin Polhemus, deputy director of the board’s division of drinking water, said at the Tuesday hearing.

This will also hardly be the first instance of repurposing sewage in California.

Utilities in the Golden State and around the country have long practiced “indirect potable reuse,” the injection of treated wastewater into environmental buffers — such as groundwater aquifers or lakes — before its discharge into a public system.

Unlike indirect potable reuse, however, DPR does not use an underground aquifer or any type of environmental storage barrier.

Instead, the process involves either sending purified wastewater directly into a treatment plant or first blending it with other water sources — a milder alternative known as “raw water augmentation” — prior to doing so.

“Toilet-to-tap is in the headlines again,” Esquivel said, noting just how “silly” some of the politics surrounding the subject has become.

He stressed that today’s reality is that anyone who is drinking from the Mississippi River, Colorado River or any other drinking water source downstream from a treatment plant “is already drinking toilet-to-tap.”

While the state board approved the rules Tuesday, DPR systems won’t be popping up overnight. The regulations first need to be accepted by the state’s Office of Administrative Law — which officials have said would likely occur by summer or fall of next year.

Only at that point would utilities begin to build these large and complex projects, most of which would take many years to complete.

Despite the widespread attention surrounding Tuesday’s vote, the Golden State is actually not be the first to approve DPR rules.

Colorado adopted DPR regulations in January, though no utilities have made use of these rules thus far. Texas released regulatory guidance for DPR on a case-by-case basis, and Florida and Arizona are both working on related rules.

Experts anticipate that the California regulations will not only be the most rigorous but will also serve commercial-scale projects that are already in planning phases.

The new DPR regulations are rooted in the 2017 A.B. 574 bill, which required the water resources board to adopt “uniform water recycling criteria for direct potable reuse” on or before Dec. 31, 2023.

The 69-page proposal details rules for controlling and monitoring chemicals and pathogens, as well as comprehensive instructions for plant operations, maintenance and compliance. 

The adoption of DPR regulations in California has faced a long, uphill battle.

San Diego, for example, launched a campaign to implement DPR in the 1990s, but this effort ultimately stalled when the “toilet-to-tap” phrase caught on and began to rock public opinion, KPBS reported. 

One long-standing issue that policymakers have identified as an obstacle toward getting Californians on board has been a discomfort associated with the potential presence of both chemicals and infectious diseases in wastewater.

But officials stressed that the proposed regulations included “triple redundancy” to ensure the elimination of biological contaminants.

To determine safe pathogen thresholds and treatment protocol, researchers relied on the Giardia and Cryptosporidium parasites and on norovirus, the most common cause of acute gastroenteritis, according to a statement of reasons issued by the board in July.

They found that regulating bacteria levels was unnecessary, as the approach for eradicating “the hardier pathogen types” could “easily deal with the bacteria threat,” the document stated.

“I’ve been at this board for seven years,” Esquivel said Tuesday, noting that it has taken many years and the leadership of prior board members to move the DPR regulations forward.

“I have to thank them first and foremost for the opportunity to be here as we adopt what are these significant regulations and really bring us here into the 21st century,” he added.