Officials and agencies in Los Angeles are examining how treated sewage water can be directly put into the drinking water system.
“There’s been a health legacy where sanitary engineering practices and regulators considered sewage a waste, it was something to be avoided, something to be feared,” Brad Coffey of the Metropolitan Water District of Southern California told Los Angeles Times.
“Now that we have the technology … the public, the regulators, the scientific community has much greater confidence in our ability to safely reuse that water supply,” Coffey said.
Under consideration by city authorities is “direct potable reuse,” which varies from “indirect potable reuse,” where recycled water is in a place with environmental barriers such as underground aquifers or reservoirs before being consumed by humans, according to LA Times.
A few decades ago, such recycling was unthinkable.
In the 1990s, when California agencies worked on taking advantage of wastewater to replenish groundwater in San Gabriel Valley and the city of Los Angeles, community groups brought lawsuits against the projects, citing the risk of adverse environmental impact, LA Times reported
However, as drought conditions worsen in California and the Western United States, opposition to such projects has “softened,” according to LA Times.
Two wastewater recycling initiatives are under development in Los Angeles County, the LA Times reported.
One is a $3.4 billion plant at the Joint Water Pollution Control Plant in Carson, California.
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The other one is an approximately $16 billion plan called Operation Next, which hopes to purify almost all of the wastewater the Hyperion Water Reclamation Plant processes, according to the outlet.
“Our goal is really to turn the largest discharge of treated wastewater in Southern California into an engine for groundwater replenishment,” Coffey told the newspaper.
“That’s in an attempt to interrupt, break the snowpack-dependent water cycle of much of California and much of the West … that’s threatened by climate change,” he added.
However, challenges remain in implementing such an ambitious initiative, most notably with the centralized structure of sewer systems.
“We have built a very highly centralized system, and it’s sort of a once-through system,” Pacific Institute Research Director Heather Cooley told the LA Times.
“We often build recycled wastewater treatment facilities at a low point in the watershed … and all the pipes are sort of oriented towards that,” Cooley said.
Another challenge in implementing the project is ensuring the water recycled is safe for public consumption and adjusting regulations accordingly.
“The key for what we’re trying to do is always protect public health, so when we’re writing these regulations, our focus is on protecting public health,” California State Water Board Technical Operations Chief – Drinking Water Randy Barnard told LA Times.
At present, there’s no way to monitor chemicals and pathogens in sewage water in real time.
Water treatment operators use a concept known as log removal to judge the number of impurities in water, according to the LA Times. For some viruses, state authorities require up to 20 log removals for water to be judged safe.
“We get accused of that sometimes that we’re too conservative, but it’s because we have public health at risk,” Barnard said.
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