After reviewing the recommendations of an expert panel and advisory group, created as part of legislation that directed the State Water Board to explore the viability of creating rules for direct potable reuse (DPR), the Board’s Division of Drinking Water has determined it is feasible to begin the process of developing regulations. However, such regulations can only be adopted provided that certain research and key knowledge gaps are addressed, according to the Board.
DPR is the addition of recycled water directly into a public water system or raw water supply just upstream of a water-treatment plant. To date, no other state has developed regulations specifically for such reuse.
The step toward regulating DPR is one of those intended to further Gov. Brown’s goal of a more sustainable water-management strategy, as laid out in the California Water Action Plan, part of which is to increase the use of recycled water, according to the Board.
“As we face a fifth year of record-breaking drought, and ongoing changes in our environment related to climate change— which could mean more droughts in our future— expanding our water resource options is a smart thing to do,” stated State Water Board Chair Felicia Marcus, in a press release. “We need to take a thoughtful and deliberate approach to diversifying and securing our long-term water resilience. Today’s draft, focused on the feasibility of direct potable reuse, is one part of a multifaceted effort that includes a wide range of sources, including indirect potable reuse through groundwater recharge, surface water augmentation, storm water capture and desalination. The release of [the] draft report is a historic step in bringing online a potential future source of potable water.”
Although the adoption of regulations related to the DPR of recycled water will not occur until the knowledge deficiencies are addressed and additional research is completed related to the protection of public health, the development of the criteria for the use of DPR will move forward, Board officials said. Due to the ongoing process, officials cannot yet provide an exact timeframe as to when regulations for the DPR of recycled water will be in place.
Some of the Division of Drinking Water’s recommendations for moving forward on the development of DPR include: convening technical workgroups to assist in developing uniform water recycling criteria for direct potable reuse; convening a “blue ribbon” panel to review scientific literature and report on the current state of scientific knowledge regarding the risks of emerging contaminants to public health; developing new methods to evaluate the performance and reliability of DPR treatment; developing more comprehensive analytical methods for unknown contaminants; addressing important implementation issues, including training and certification of operators for potable reuse treatment facilities, optimizing wastewater treatment plant performance to prepare for DPR, enhancing source control programs designed to prevent or minimize discharges of toxic chemicals to sewer systems that feed into DPR treatment plants and ensuring that agencies implementing DPR projects have adequate technical, managerial, and financial capacity to ensure the success and safety of the project; and working with regional water-quality control boards to include monitoring for pathogens in raw wastewater feeding potable reuse systems.
“What ‘raw wastewater’ means is raw sewage,” Andrew DiLuccia, public information officer with the State Water Resources Control Board, told the Signal Tribune. “So, what is being asked is that the raw sewage be tested for pathogens to see what’s in it before it begins the treatment process.”
One such agency that would monitor for those pathogens is the Sanitation Districts of Los Angeles County, which constitute a public agency created under state law to manage wastewater and solid waste on a regional scale and consist of 24 independent special districts serving about 5.5 million people in the county, according to the agency’s website.
“From the Sanitation Districts’ perspective, the high amount of solids in raw wastewater presents challenges to accurately determining pathogen levels,” said Philip Friess, department head of technical services for the agency, in an email to the Signal Tribune. “We have very limited experience, during a few research projects, at trying to measure pathogens in raw wastewater. The Sanitation Districts routinely test all of its treated water, which has very low solids content, to ensure compliance with indicator bacteria limits and demonstrate protection of public health and the environment that we discharge to. In addition, recycled water that is used to recharge groundwater aquifers is tested for human enteric viruses, which include pathogens, but again, this water has very low solids content.”
In his email to the Signal Tribune, Friess said his agency expects testing for purified water used for DPR to have very stringent pathogen analysis requirements.
“At this time, we believe testing the finished water is much more critical than testing the incoming raw wastewater,” he said. “We support the State’s efforts to prepare safe and scientifically driven regulations that will help Californians meet their water supply needs in a more sustainable manner. We look forward to participating in the development of these regulations.”
DiLuccia clarified what the source of the wastewater would be.
“When regulations are adopted, there would be an available supply of treated recycled water, which would come in the form of treated recycled wastewater that comes from wastewater treatment plants,” he said.
Signal Hill Councilmember Larry Forester, a civil engineer who studied sanitary engineering and serves on the LA County Sanitation Districts board, said he agrees that recycled water could indeed be converted into potable water, as long as the proper treatments are undertaken.
“I would suspect that some sort of nanofiltration process would have to be used to clean up the recycled water,” Forester said.
He explained that, in the treatment of sanitary water, there are three stages— primary, secondary and tertiary. “Tertiary is virtually clean water but would need one further step to make it potable,” he said. “The first two are strictly treated water, and they are not usable for drinking water. It has to go through a tertiary treatment, and then, after the tertiary treatment, it has to go through a further treatment for potable water, which probably is a form of nanofiltration.”
Forester said the water that would be added upstream of treatment plants would need to be water that has gone through such a process.
“Is it doable? Yes,” Forester said. “Any cruise line you take right now takes your sanitary water, filters it, uses reverse osmosis, and it comes back as drinking water. Your cruise lines are self-contained water systems.”
Forester also mentioned that, per current regulations, the water that makes its way to faucets will need other chemicals, such as fluoride, added to it.
The draft report is available now for comment under a 45-day public review period before finalization and presentation to the state Legislature by Dec. 31, 2016.
