California to vote on allowing ‘toilet-to-tap’ projects: What to know
Sharon Udasin
Sharon Udasin
THE HILL
Sat, December 16, 2023
Some Californians could find themselves flushing a future drinking water source down their commodes in just a few years’ time — pending the approval of long-awaited, but misnamed, “toilet-to-tap” rules next week.
The California State Water Resources Control Board will consider a landmark proposal Tuesday to streamline “direct potable reuse” (DPR) — a process by which purified wastewater is discharged right into a public water system or just upstream from a treatment plant.
“It’s a real important step for just adding to the portfolio that we can use here in the West,” Darrin Polhemus, deputy director of the board’s division of drinking water, told The Hill.
Such capabilities, he explained, could strengthen California’s water resilience, while providing numerous environmental benefits and reducing the need for long-distance water transport.
“We’re not using it one time and dumping it in the ocean,” Polhemus said.
While these regulations would constitute a giant leap forward in statewide water recycling, California utilities are by no means new to repurposing sewage.
They have for years engaged in “indirect potable reuse,” the injection of treated wastewater into environmental buffers — such as groundwater aquifers, lakes or rivers — before its ultimate release into a municipal system.
Orange County, which has treated sewage in some capacity since the 1970s, now boasts the world’s biggest water purification system for indirect potable reuse. Today, the county claims to be reclaiming 100 percent of its wastewater.
Unlike indirect potable reuse, however, DPR occurs without the use of an underground aquifer or any environmental storage barrier.
Even if the board does approve the rules Tuesday, DPR systems won’t be popping up overnight — and when they do, the wastewater won’t really be flowing right from a toilet to a tap.
The regulations first would have to be accepted by the state’s Office of Administrative Law — which Polhemus said would likely occur by summer or fall of next year. Only after that could utilities begin to build these large and complex projects, most of which would take about six or seven years to complete, he said.
“So no one will be drinking direct potable reuse in the immediate future,” Polhemus added.
Tapping into an existing system, over and over again
While California is often a national trailblazer when it comes to environmental regulation and legislation, the Golden State would not be the first to adopt rules regarding DPR.
Colorado adopted DPR regulations after updating its drinking water standards in January, though no utilities are making use of these rules thus far. Texas published regulatory guidance for DPR on a case-by-case basis, while Florida and Arizona are now working on related rules.
The California regulations, however, are expected not only to be the most rigorous, but would be serving several commercial-scale projects that are already in planning phases.
The proposed regulations stem from the 2017 A.B. 574 bill, which tasked the water resources board with adopting “uniform water recycling criteria for direct potable reuse” on or before Dec. 31, 2023.
Within the regulations are mandates that all source water for DPR projects come from municipal sewage and a ban on building bypasses to circumvent mandatory treatment processes.
The 69-page proposal also provides guidelines for controlling and monitoring chemicals and pathogens, as well as extensive instructions for plant operations, maintenance and compliance.
Among the expected benefits of the proposed regulations are the provision of a safe, reliable and drought-proof drinking water supply, as well as a streamlined permitting procedure for DPR facilities, according to a statement of reasons issued by the board in July.
As far as the economics are concerned, Polhemus noted that DPR would enable utilities to reduce some of the expensive and disruptive pipeline and infrastructure construction that comes with other types of water recycling efforts.
“DPR does provide this opportunity to tap into the potable water distribution system that exists already,” he said.
Polhemus acknowledged that DPR is expensive but stressed it is far cheaper than desalination. Even when cities develop new natural water sources — which are largely unavailable in California — they confront “phenomenally high” costs for dams and aqueducts, he added.
Getting the public on board
Despite the many potential benefits associated with directly recycling wastewater, California regulators have faced an uphill battle in making this practice a reality.
For example, San Diego launched a campaign to implement DPR in the 1990s, but the plans stalled when a “toilet to tap” misnomer caught on and began to sway public opinion, KPBS reported.
Public opinion on DPR has evolved since the days of the San Diego debacle — both as the science has become clearer and California’s water needs have become more dire.
Jennifer West, managing director at the NGO WateReuse California, said she believes DPR has become more palatable to Californians as they have begun to understand the value of water amid multiple decades of drought.
“Using water one time and discharging it — we can do better than that,” she told The Hill.
West said she has seen a shift in “the collective consciousness” of Californians, noting that residents now complain when their cities aren’t reclaiming enough wastewater.
Polhemus likewise attributed the increasing public acceptance to the fact that water recycling — at least in indirect form — has now been occurring for a long time.
“For decades, we’ve learned from all of the activities we’ve done for recycling — from irrigation to indirect potable reuse,” he added, describing DPR as “the final step.”
If the regulations are approved, they would also require engagement with members of the public prior to the establishment of any DPR facility, according to Polhemus.
“We want the public to be brought along, to be explained what’s going on and be part of that decision-making process,” he said.
Emphasizing that “we’re not imposing this on anybody,” Polhemus reiterated that the board is simply providing utilities with a framework if they so choose to build a facility.
One long-standing issue that he and others identified as a barrier toward getting the public on board has been a discomfort linked to the potential presence of both chemicals and infectious diseases in wastewater.
Polhemus stressed, however, that the proposed regulations included “triple redundancy” to ensure the elimination of biological contaminants.
To identify an acceptable pathogen threshold and treatment protocol, researchers relied upon both the Giardia and Cryptosporidium parasites and on norovirus, the most common cause of acute gastroenteritis, according to the July statement of reasons.
They determined that regulating bacteria levels was unnecessary, as the treatment for handling “the hardier pathogen types” could “easily deal with the bacteria threat,” the document stated.
“The regulations are extremely protective of public health, and it’s going to be the cleanest water around,” West added.
On the chemical side, Polhemus touted an effective combination of reverse osmosis, advanced oxidation and granulated activated carbon.
That redundancy, he contended, gives regulators “the confidence that we’ll be able to treat for things we don’t even know are there.”
‘A community’s always going to produce wastewater’
If the DPR regulations receive an official stamp of approval, there are several Southern California projects prepared to embark on a multi-year planning and construction journey.
Among these projects is Pure Water San Diego, a multi-phased program to provide nearly half of San Diego’s water from local sources by the end of 2035.
Although the first phase of Pure Water San Diego will use a reservoir for indirect potable reuse, the city is considering incorporating DPR into the next phase, according to the plans.
The Metropolitan Water District of Southern California, meanwhile, is partnering with Los Angeles County Sanitation Districts on a two-phased initiative, Pure Water Southern California, which plans to include DPR from the get-go.
The first phase is expected to involve a mix of indirect potable use and a type of DPR called “raw water augmentation,” in which treated wastewater would be blended with imported Colorado River water and state resources.
This process still qualifies as DPR because the mix would go directly into a drinking water treatment plant and on to customers, rather than first spending time in an environmental buffer.
“Our plan is to have Pure Water Southern California online and using DPR by 2032,” Rebecca Kimitch, press office manager for Metropolitan Water District, told The Hill.
As far as the second phase is concerned, project officials said they have yet to decide whether the DPR technology will again involve raw water augmentation or another approach.
“DPR is a vital component of our Pure Water Southern California program as well as to California’s water management strategy as a whole,” Kimitch said.
“But DPR will allow us to take this stream of purified water and incorporate it into our system right away, regardless of what the conditions in nature are,” she added.
Because Southern California lacks the natural resources to quench the thirst of its residents, the region has been relying on bringing in water from the Colorado River and from the northern parts of the state, Kimitch noted.
“We want to just use it as much as we can,” she continued. “Using it once and then sending it to the ocean — that’s not being as efficient and as sustainable as we can be.”
Polhemus echoed many of these sentiments, noting that as utilities consider how to bolster its resilience amid drought, adding DPR to their portfolios simply “makes a lot of sense.”
“A community’s always going to produce wastewater,” he said.
Sat, December 16, 2023
Some Californians could find themselves flushing a future drinking water source down their commodes in just a few years’ time — pending the approval of long-awaited, but misnamed, “toilet-to-tap” rules next week.
The California State Water Resources Control Board will consider a landmark proposal Tuesday to streamline “direct potable reuse” (DPR) — a process by which purified wastewater is discharged right into a public water system or just upstream from a treatment plant.
“It’s a real important step for just adding to the portfolio that we can use here in the West,” Darrin Polhemus, deputy director of the board’s division of drinking water, told The Hill.
Such capabilities, he explained, could strengthen California’s water resilience, while providing numerous environmental benefits and reducing the need for long-distance water transport.
“We’re not using it one time and dumping it in the ocean,” Polhemus said.
While these regulations would constitute a giant leap forward in statewide water recycling, California utilities are by no means new to repurposing sewage.
They have for years engaged in “indirect potable reuse,” the injection of treated wastewater into environmental buffers — such as groundwater aquifers, lakes or rivers — before its ultimate release into a municipal system.
Orange County, which has treated sewage in some capacity since the 1970s, now boasts the world’s biggest water purification system for indirect potable reuse. Today, the county claims to be reclaiming 100 percent of its wastewater.
Unlike indirect potable reuse, however, DPR occurs without the use of an underground aquifer or any environmental storage barrier.
Even if the board does approve the rules Tuesday, DPR systems won’t be popping up overnight — and when they do, the wastewater won’t really be flowing right from a toilet to a tap.
The regulations first would have to be accepted by the state’s Office of Administrative Law — which Polhemus said would likely occur by summer or fall of next year. Only after that could utilities begin to build these large and complex projects, most of which would take about six or seven years to complete, he said.
“So no one will be drinking direct potable reuse in the immediate future,” Polhemus added.
Tapping into an existing system, over and over again
While California is often a national trailblazer when it comes to environmental regulation and legislation, the Golden State would not be the first to adopt rules regarding DPR.
Colorado adopted DPR regulations after updating its drinking water standards in January, though no utilities are making use of these rules thus far. Texas published regulatory guidance for DPR on a case-by-case basis, while Florida and Arizona are now working on related rules.
The California regulations, however, are expected not only to be the most rigorous, but would be serving several commercial-scale projects that are already in planning phases.
The proposed regulations stem from the 2017 A.B. 574 bill, which tasked the water resources board with adopting “uniform water recycling criteria for direct potable reuse” on or before Dec. 31, 2023.
Within the regulations are mandates that all source water for DPR projects come from municipal sewage and a ban on building bypasses to circumvent mandatory treatment processes.
The 69-page proposal also provides guidelines for controlling and monitoring chemicals and pathogens, as well as extensive instructions for plant operations, maintenance and compliance.
Among the expected benefits of the proposed regulations are the provision of a safe, reliable and drought-proof drinking water supply, as well as a streamlined permitting procedure for DPR facilities, according to a statement of reasons issued by the board in July.
As far as the economics are concerned, Polhemus noted that DPR would enable utilities to reduce some of the expensive and disruptive pipeline and infrastructure construction that comes with other types of water recycling efforts.
“DPR does provide this opportunity to tap into the potable water distribution system that exists already,” he said.
Polhemus acknowledged that DPR is expensive but stressed it is far cheaper than desalination. Even when cities develop new natural water sources — which are largely unavailable in California — they confront “phenomenally high” costs for dams and aqueducts, he added.
Getting the public on board
Despite the many potential benefits associated with directly recycling wastewater, California regulators have faced an uphill battle in making this practice a reality.
For example, San Diego launched a campaign to implement DPR in the 1990s, but the plans stalled when a “toilet to tap” misnomer caught on and began to sway public opinion, KPBS reported.
Public opinion on DPR has evolved since the days of the San Diego debacle — both as the science has become clearer and California’s water needs have become more dire.
Jennifer West, managing director at the NGO WateReuse California, said she believes DPR has become more palatable to Californians as they have begun to understand the value of water amid multiple decades of drought.
“Using water one time and discharging it — we can do better than that,” she told The Hill.
West said she has seen a shift in “the collective consciousness” of Californians, noting that residents now complain when their cities aren’t reclaiming enough wastewater.
Polhemus likewise attributed the increasing public acceptance to the fact that water recycling — at least in indirect form — has now been occurring for a long time.
“For decades, we’ve learned from all of the activities we’ve done for recycling — from irrigation to indirect potable reuse,” he added, describing DPR as “the final step.”
If the regulations are approved, they would also require engagement with members of the public prior to the establishment of any DPR facility, according to Polhemus.
“We want the public to be brought along, to be explained what’s going on and be part of that decision-making process,” he said.
Emphasizing that “we’re not imposing this on anybody,” Polhemus reiterated that the board is simply providing utilities with a framework if they so choose to build a facility.
One long-standing issue that he and others identified as a barrier toward getting the public on board has been a discomfort linked to the potential presence of both chemicals and infectious diseases in wastewater.
Polhemus stressed, however, that the proposed regulations included “triple redundancy” to ensure the elimination of biological contaminants.
To identify an acceptable pathogen threshold and treatment protocol, researchers relied upon both the Giardia and Cryptosporidium parasites and on norovirus, the most common cause of acute gastroenteritis, according to the July statement of reasons.
They determined that regulating bacteria levels was unnecessary, as the treatment for handling “the hardier pathogen types” could “easily deal with the bacteria threat,” the document stated.
“The regulations are extremely protective of public health, and it’s going to be the cleanest water around,” West added.
On the chemical side, Polhemus touted an effective combination of reverse osmosis, advanced oxidation and granulated activated carbon.
That redundancy, he contended, gives regulators “the confidence that we’ll be able to treat for things we don’t even know are there.”
‘A community’s always going to produce wastewater’
If the DPR regulations receive an official stamp of approval, there are several Southern California projects prepared to embark on a multi-year planning and construction journey.
Among these projects is Pure Water San Diego, a multi-phased program to provide nearly half of San Diego’s water from local sources by the end of 2035.
Although the first phase of Pure Water San Diego will use a reservoir for indirect potable reuse, the city is considering incorporating DPR into the next phase, according to the plans.
The Metropolitan Water District of Southern California, meanwhile, is partnering with Los Angeles County Sanitation Districts on a two-phased initiative, Pure Water Southern California, which plans to include DPR from the get-go.
The first phase is expected to involve a mix of indirect potable use and a type of DPR called “raw water augmentation,” in which treated wastewater would be blended with imported Colorado River water and state resources.
This process still qualifies as DPR because the mix would go directly into a drinking water treatment plant and on to customers, rather than first spending time in an environmental buffer.
“Our plan is to have Pure Water Southern California online and using DPR by 2032,” Rebecca Kimitch, press office manager for Metropolitan Water District, told The Hill.
As far as the second phase is concerned, project officials said they have yet to decide whether the DPR technology will again involve raw water augmentation or another approach.
“DPR is a vital component of our Pure Water Southern California program as well as to California’s water management strategy as a whole,” Kimitch said.
“But DPR will allow us to take this stream of purified water and incorporate it into our system right away, regardless of what the conditions in nature are,” she added.
Because Southern California lacks the natural resources to quench the thirst of its residents, the region has been relying on bringing in water from the Colorado River and from the northern parts of the state, Kimitch noted.
“We want to just use it as much as we can,” she continued. “Using it once and then sending it to the ocean — that’s not being as efficient and as sustainable as we can be.”
Polhemus echoed many of these sentiments, noting that as utilities consider how to bolster its resilience amid drought, adding DPR to their portfolios simply “makes a lot of sense.”
“A community’s always going to produce wastewater,” he said.
California prepares to transform sewage into pure drinking water under new rules
Ian James
Sun, December 17, 2023
Rupam Soni speaks during a tour of the Metropolitan Water District's pilot water recycling facility in Carson. (Christina House / Los Angeles Times)
California is set to adopt regulations that will allow for sewage to be extensively treated, transformed into pure drinking water and delivered directly to people’s taps.
The regulations are expected to be approved Tuesday by the State Water Resources Control Board, enabling water suppliers to begin building advanced treatment plants that will turn wastewater into a source of clean drinking water.
The new rules represent a major milestone in California’s efforts to stretch supplies by recycling more of the water that flows down drains.
“We're creating a new source of supply that we were previously discharging or thinking of as waste,” said Heather Cooley, director of research at the Pacific Institute, a water think tank in Oakland. “As we look to make our communities more resilient to drought, to climate change, this is really going to be an important part of that solution.”
Water agencies in many areas of California have been treating and reusing wastewater for decades, often piping effluent for outdoor irrigation or to facilities where treated water soaks into the ground to replenish aquifers.
The regulations will enable what’s known as “direct potable reuse,” putting highly treated water straight into the drinking-water system or mixing it with other supplies.
Read more: With California expected to lose 10% of its water within 20 years, Newsom calls for urgent action
Cooley and other water experts say it’s inaccurate to call this “toilet to tap,” a term that was popularized in the 1990s by opponents of plans to use recycled water for replenishing groundwater in the San Gabriel Valley. They say the sewage undergoes an extremely sophisticated treatment process, and scientific research has shown that the highly purified water is safe to drink.
“This is really about recovering resources, not wasting precious resources,” Cooley said. “This is really, I think, an exciting opportunity for helping to realize that vision of a more circular sort of approach for water.”
The process of developing the regulations, which was required under legislation, has taken state regulators more than a decade. It included a review by a panel of experts.
“We wanted to absolutely make sure that we put public health first priority, so that the public had confidence,” said Darrin Polhemus, deputy director of the State Water Board’s Division of Drinking Water.
“We have a very thorough set of regulations,” Polhemus said. “It has broad support, and we think we've gotten it to a point where everybody is comfortable with what it presents.”
Building plants to purify wastewater is expensive, and it’s likely to be years before any Californians are drinking the treated water. But Los Angeles, San Diego and the Metropolitan Water District of Southern California are all planning to pursue direct potable reuse as part of ongoing investments in recycling more wastewater.
The regulations detail requirements for infrastructure, treatment technologies and monitoring, Polhemus said, and ensure “triple redundancy for each of the areas we’re treating for,” including bacteria and viruses, as well as chemicals.
The water will go through various stages of treatment, passing through activated carbon filters and reverse-osmosis membranes, as well as undergoing disinfection with UV light, among other treatments.
The regulations require such thorough purification that at the end of the process, minerals will need to be added back to achieve a taste and chemistry resembling typical drinking water.
“This will be by far the most well-treated, highest-quality water served to the public,” Polhemus said. “It's an incredible amount of treatment.”
Read more: California could shrink water use in cities by 30% or more, study finds
Once the regulations are approved by the State Water Board, they need to be approved by the Office of Administrative Law; this is expected to happen next year.
The treatment technology is similar to the process used for desalinating seawater, but recycling wastewater requires less energy and is less costly than turning saltwater into freshwater. Polhemus said the costs for purifying wastewater will probably be about half those of desalinating ocean water.
Direct potable reuse has for years been a strategy in other water-scarce parts of the world, including Namibia and Singapore. Some communities in Texas are also doing it. Colorado has rules in place allowing potable reuse, while Arizona and Florida are developing regulations.
In California, some agencies have for years been conducting indirect potable reuse, in which highly treated water is used to replenish groundwater and is later pumped out, treated and delivered as drinking water.
Orange County, for example, has its Groundwater Replenishment System, the world's largest project of its kind . The system purifies wastewater using a three-step advanced treatment process, and the water then percolates and is injected into the groundwater basin, where it becomes part of the supply.
While Orange County plans to stick with indirect potable reuse, Polhemus said, other water districts are looking at direct reuse as an approach that saves costs by using existing infrastructure rather than building separate systems for recycled water.
This strategy also offers cities and agencies a new route for reducing reliance on imported supplies and scaling up the use of recycled water — a source that managers view as relatively drought-proof.
“Our communities are always going to generate wastewater, even in the worst drought. And having this available can really augment that supply and add resiliency,” Polhemus said.
Read more: Los Angeles could soon put recycled water directly in your tap. It's not 'toilet to tap'
Recycling more wastewater brings other environmental benefits, reducing the amount of treated effluent that flows into coastal waters.
“It's easier on the environment you're taking the water from, it's easier on the environment you're discharging it to and sets us up to be better stewards of our environment overall,” Polhemus said.
The complexity and costs of the treatment plants mean that large, well-funded agencies will adopt the technology first, Polhemus said. Direct potable reuse also is suited to coastal areas, he said, because the reverse-osmosis treatment, like a desalination plant, generates brine that can be discharged offshore.
As for how much purified water might be used, if some coastal communities are able to get 10%-15% of their supply from treated wastewater during a drought, that would represent a significant improvement in diversifying supplies, Polhemus said.
“Someday, it could be 25% to 40% of some communities' water supply,” Polhemus said. “At some point, we could recycle the majority of wastewater that now flows to the ocean just as treated wastewater.”
The Metropolitan Water District plans to start direct potable reuse as part of its Pure Water Southern California project, building a $6-billion facility in Carson that is slated to become the country’s largest water-recycling project.
It’s scheduled to deliver its first treated water as soon as 2028. Initially, the district says, the supplies will be used largely to replenish groundwater basins for later use, with some also going to serve oil refineries and other industrial users.
By 2032, MWD officials plan to be producing 115 million gallons of purified water a day. Of that, they expect to send 25 million gallons per day to a plant in La Verne to be mixed with other supplies from the Colorado River and Northern California, and delivered as drinking water throughout the region — an amount that’s projected to increase to 60 million gallons a day once the facility is operating at its full capacity of 150 million gallons .
Read more: Southern California’s ‘water doctor’ pushes for transformation to adapt to climate change
Depending on how wet or dry a year is, the district will be able to store more water in aquifers or send more purified water directly into the distribution system, said Deven Upadhyay, the MWD’s executive officer and assistant general manager.
“We're building that flexibility into the design of this program,” Upadhyay said. “If you needed to push more into direct potable reuse, you would be able to do that and back off of your deliveries to the groundwater basins.”
He said that flexibility is valuable as California deals with more extreme droughts fueled by climate change.
“Our view is that over time, those imported supplies will decline. And we want to take the water that is used, and reuse it as much as possible, and try to close that cycle of water use,” Upadhyay said. "Because it's such a drought-proof supply, it really creates another degree of resilience for us."
The Metropolitan Water District functions as Southern California’s wholesaler, delivering supplies to cities and agencies that serve 19 million people in six counties.
About 450,000 acre-feet of wastewater is now recycled in Metropolitan’s service area, an amount equivalent to the water use of about 1.3 million households.
The MWD’s recycling project, as well as Los Angeles’ Operation Next and San Diego’s Pure Water , will dramatically increase the use of recycled water once they are built out, Upadhyay said.
“We should expect a doubling of recycled water that Southern California is producing and drinking by the time those three projects are completed,” Upadhyay said.
And part of that will come thanks to the state’s new regulations that enable direct reuse, he said.
“It's a major milestone for the state,” Upadhyay said. “This is going to lead to water agencies throughout the state starting to plan for potable reuse projects in a way that results in a more resilient California water future.”
Read more: A California dry farmer's juicy apples show how agriculture can be done with less water
In the Bay Area, the Santa Clara Valley Water District also plans to pursue potable reuse.
In a study last year, researchers at the Pacific Institute said California recycles about 23% of its municipal wastewater and has the potential to more than triple the amount that is recycled and reused.
Cooley said some portion of that will come through direct reuse where it pencils out for communities.
“It's just part of the puzzle in terms of helping us to realize the full potential for recycled water,” Cooley said. “This is an important piece of helping make our communities more resilient.”
There has been growing public acceptance of recycling water as people have experienced more severe droughts and seen recycling projects expand, Cooley said.
Still, she said, acceptance isn’t universal, and “it's important to really address openly concerns that people have as communities consider this as an option.”
She said reusing more water is one strategy that California should adopt, along with capturing more stormwater and improving efficiency.
Peter Gleick, the Pacific Institute’s co-founder and president emeritus, pointed out that the water-recycling technologies in use today are fundamentally the same approaches used by astronauts on the International Space Station.
“It’s not toilet to tap,” Gleick said, adding that it’s better described as “toilet to an unbelievably sophisticated system that produces incredibly pure water to tap.”
In his book “The Three Ages of Water,” Gleick wrote that reusing water provides a valuable new supply and should be part of a set of solutions for long-term sustainability.
“High-quality water produced from wastewater is an asset,” Gleick wrote. “We have the ability and technology to produce incredibly clean water from any quality of wastewater, and we should rapidly expand the capacity to do so.”
This story originally appeared in Los Angeles Times.
Ian James
Sun, December 17, 2023
Rupam Soni speaks during a tour of the Metropolitan Water District's pilot water recycling facility in Carson. (Christina House / Los Angeles Times)
California is set to adopt regulations that will allow for sewage to be extensively treated, transformed into pure drinking water and delivered directly to people’s taps.
The regulations are expected to be approved Tuesday by the State Water Resources Control Board, enabling water suppliers to begin building advanced treatment plants that will turn wastewater into a source of clean drinking water.
The new rules represent a major milestone in California’s efforts to stretch supplies by recycling more of the water that flows down drains.
“We're creating a new source of supply that we were previously discharging or thinking of as waste,” said Heather Cooley, director of research at the Pacific Institute, a water think tank in Oakland. “As we look to make our communities more resilient to drought, to climate change, this is really going to be an important part of that solution.”
Water agencies in many areas of California have been treating and reusing wastewater for decades, often piping effluent for outdoor irrigation or to facilities where treated water soaks into the ground to replenish aquifers.
The regulations will enable what’s known as “direct potable reuse,” putting highly treated water straight into the drinking-water system or mixing it with other supplies.
Read more: With California expected to lose 10% of its water within 20 years, Newsom calls for urgent action
Cooley and other water experts say it’s inaccurate to call this “toilet to tap,” a term that was popularized in the 1990s by opponents of plans to use recycled water for replenishing groundwater in the San Gabriel Valley. They say the sewage undergoes an extremely sophisticated treatment process, and scientific research has shown that the highly purified water is safe to drink.
“This is really about recovering resources, not wasting precious resources,” Cooley said. “This is really, I think, an exciting opportunity for helping to realize that vision of a more circular sort of approach for water.”
The process of developing the regulations, which was required under legislation, has taken state regulators more than a decade. It included a review by a panel of experts.
“We wanted to absolutely make sure that we put public health first priority, so that the public had confidence,” said Darrin Polhemus, deputy director of the State Water Board’s Division of Drinking Water.
“We have a very thorough set of regulations,” Polhemus said. “It has broad support, and we think we've gotten it to a point where everybody is comfortable with what it presents.”
Building plants to purify wastewater is expensive, and it’s likely to be years before any Californians are drinking the treated water. But Los Angeles, San Diego and the Metropolitan Water District of Southern California are all planning to pursue direct potable reuse as part of ongoing investments in recycling more wastewater.
The regulations detail requirements for infrastructure, treatment technologies and monitoring, Polhemus said, and ensure “triple redundancy for each of the areas we’re treating for,” including bacteria and viruses, as well as chemicals.
The water will go through various stages of treatment, passing through activated carbon filters and reverse-osmosis membranes, as well as undergoing disinfection with UV light, among other treatments.
The regulations require such thorough purification that at the end of the process, minerals will need to be added back to achieve a taste and chemistry resembling typical drinking water.
“This will be by far the most well-treated, highest-quality water served to the public,” Polhemus said. “It's an incredible amount of treatment.”
Read more: California could shrink water use in cities by 30% or more, study finds
Once the regulations are approved by the State Water Board, they need to be approved by the Office of Administrative Law; this is expected to happen next year.
The treatment technology is similar to the process used for desalinating seawater, but recycling wastewater requires less energy and is less costly than turning saltwater into freshwater. Polhemus said the costs for purifying wastewater will probably be about half those of desalinating ocean water.
Direct potable reuse has for years been a strategy in other water-scarce parts of the world, including Namibia and Singapore. Some communities in Texas are also doing it. Colorado has rules in place allowing potable reuse, while Arizona and Florida are developing regulations.
In California, some agencies have for years been conducting indirect potable reuse, in which highly treated water is used to replenish groundwater and is later pumped out, treated and delivered as drinking water.
Orange County, for example, has its Groundwater Replenishment System, the world's largest project of its kind . The system purifies wastewater using a three-step advanced treatment process, and the water then percolates and is injected into the groundwater basin, where it becomes part of the supply.
While Orange County plans to stick with indirect potable reuse, Polhemus said, other water districts are looking at direct reuse as an approach that saves costs by using existing infrastructure rather than building separate systems for recycled water.
This strategy also offers cities and agencies a new route for reducing reliance on imported supplies and scaling up the use of recycled water — a source that managers view as relatively drought-proof.
“Our communities are always going to generate wastewater, even in the worst drought. And having this available can really augment that supply and add resiliency,” Polhemus said.
Read more: Los Angeles could soon put recycled water directly in your tap. It's not 'toilet to tap'
Recycling more wastewater brings other environmental benefits, reducing the amount of treated effluent that flows into coastal waters.
“It's easier on the environment you're taking the water from, it's easier on the environment you're discharging it to and sets us up to be better stewards of our environment overall,” Polhemus said.
The complexity and costs of the treatment plants mean that large, well-funded agencies will adopt the technology first, Polhemus said. Direct potable reuse also is suited to coastal areas, he said, because the reverse-osmosis treatment, like a desalination plant, generates brine that can be discharged offshore.
As for how much purified water might be used, if some coastal communities are able to get 10%-15% of their supply from treated wastewater during a drought, that would represent a significant improvement in diversifying supplies, Polhemus said.
“Someday, it could be 25% to 40% of some communities' water supply,” Polhemus said. “At some point, we could recycle the majority of wastewater that now flows to the ocean just as treated wastewater.”
The Metropolitan Water District plans to start direct potable reuse as part of its Pure Water Southern California project, building a $6-billion facility in Carson that is slated to become the country’s largest water-recycling project.
It’s scheduled to deliver its first treated water as soon as 2028. Initially, the district says, the supplies will be used largely to replenish groundwater basins for later use, with some also going to serve oil refineries and other industrial users.
By 2032, MWD officials plan to be producing 115 million gallons of purified water a day. Of that, they expect to send 25 million gallons per day to a plant in La Verne to be mixed with other supplies from the Colorado River and Northern California, and delivered as drinking water throughout the region — an amount that’s projected to increase to 60 million gallons a day once the facility is operating at its full capacity of 150 million gallons .
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Depending on how wet or dry a year is, the district will be able to store more water in aquifers or send more purified water directly into the distribution system, said Deven Upadhyay, the MWD’s executive officer and assistant general manager.
“We're building that flexibility into the design of this program,” Upadhyay said. “If you needed to push more into direct potable reuse, you would be able to do that and back off of your deliveries to the groundwater basins.”
He said that flexibility is valuable as California deals with more extreme droughts fueled by climate change.
“Our view is that over time, those imported supplies will decline. And we want to take the water that is used, and reuse it as much as possible, and try to close that cycle of water use,” Upadhyay said. "Because it's such a drought-proof supply, it really creates another degree of resilience for us."
The Metropolitan Water District functions as Southern California’s wholesaler, delivering supplies to cities and agencies that serve 19 million people in six counties.
About 450,000 acre-feet of wastewater is now recycled in Metropolitan’s service area, an amount equivalent to the water use of about 1.3 million households.
The MWD’s recycling project, as well as Los Angeles’ Operation Next and San Diego’s Pure Water , will dramatically increase the use of recycled water once they are built out, Upadhyay said.
“We should expect a doubling of recycled water that Southern California is producing and drinking by the time those three projects are completed,” Upadhyay said.
And part of that will come thanks to the state’s new regulations that enable direct reuse, he said.
“It's a major milestone for the state,” Upadhyay said. “This is going to lead to water agencies throughout the state starting to plan for potable reuse projects in a way that results in a more resilient California water future.”
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In the Bay Area, the Santa Clara Valley Water District also plans to pursue potable reuse.
In a study last year, researchers at the Pacific Institute said California recycles about 23% of its municipal wastewater and has the potential to more than triple the amount that is recycled and reused.
Cooley said some portion of that will come through direct reuse where it pencils out for communities.
“It's just part of the puzzle in terms of helping us to realize the full potential for recycled water,” Cooley said. “This is an important piece of helping make our communities more resilient.”
There has been growing public acceptance of recycling water as people have experienced more severe droughts and seen recycling projects expand, Cooley said.
Still, she said, acceptance isn’t universal, and “it's important to really address openly concerns that people have as communities consider this as an option.”
She said reusing more water is one strategy that California should adopt, along with capturing more stormwater and improving efficiency.
Peter Gleick, the Pacific Institute’s co-founder and president emeritus, pointed out that the water-recycling technologies in use today are fundamentally the same approaches used by astronauts on the International Space Station.
“It’s not toilet to tap,” Gleick said, adding that it’s better described as “toilet to an unbelievably sophisticated system that produces incredibly pure water to tap.”
In his book “The Three Ages of Water,” Gleick wrote that reusing water provides a valuable new supply and should be part of a set of solutions for long-term sustainability.
“High-quality water produced from wastewater is an asset,” Gleick wrote. “We have the ability and technology to produce incredibly clean water from any quality of wastewater, and we should rapidly expand the capacity to do so.”
This story originally appeared in Los Angeles Times.
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