As the pumps whir around us, Denis Bilodeau motions to the liquid in the vats below. It looks like iced tea, but in fact it’s secondary treated sewage, cleaned of any solids by the plant next door. In less than an hour, and after three steps of processing, we will be drinking it – as pure water.
The Groundwater Replenishment System facility in Orange County,California, houses the pipes, filters and pumps to move up to 130m gallons each day – enough for 1 million people – processing it from dark to clear. The facility, which opened in 2008, is part of broader moves to help conserve water.
Bilodeau, the president of the water district, says: “This is going to be a blueprint for any community that’s facing water scarcity, or wants to have more locally controlled water.”
The idea is to take the water from the sanitation district next door and to push it through a three-step process – microfiltration, reverse osmosis and ultraviolet light purification – to make clean water. The facility provides 45% of central Orange County’s water and helps manage stormwater inflows and reduce reliance on imported water.
In general, once sewage has been treated, the water is returned to our rivers, but extreme droughts and climate change are pushing cities to consider using recycled sewage for drinking water. It is already done in Israel, Singapore and Kuwait, but Orange County has been a US pioneer in this area, hoping to reduce dependence on water piped from faraway rivers or pumped from shrinking aquifers under the ground.
Orange County has a population of about 3 million and gets about 14 inches (35.5cm) of rain per year, some years far less, so recycling isn’t just a way to reduce costs, it’s a way to make sure everyone has what they need. “Everything’s going to have to be reclaimed andrecycled,” says Bilodeau.
When the liquid reaches the plant it has already been through some treatment and is clean enough to discharge into the oceans, but nowhere near clean enough to drink. The first step is to pump the water through bundles of hollow polypropylene fibres – which look like tiny plastic straws – to remove particulates as well as bacteria and other unwanted elements.
Pipes then carry the filtered water to a building to undergo reverse osmosis, where it is pushed through membranes that squeeze out the salts, organic chemicals and any pharmaceutical leftovers.
Finally, the water is blasted with high-intensity ultraviolet light and hydrogen peroxide to disinfect anything that might remain. “It’s concentrated sunlight,” Bilodeau says, “like what you would see in a tanning booth.” Except this would injure your eyes, because it’s so strong.
After walking around all three buildings, we reach a sink with running, clear water. I drink a cup of the stuff, expecting a whiff of what it used to be – but no, it’s super clean, with almost a flat taste. That’s because it no longer contains any salts or minerals – they have been blasted out by the cleaning process.
On the cup is a motto, “Tastes like water … because it is water”, chosen because it is the number one comment, says Mehul Patel, the executive director of operations at the Orange CountyWaterDistrict, who oversees the facility. “There was a misperception that it tastes different or tastes like something,” he says. “We’re trying to show people scientifically, water is just water.”
“We wanted full transparency,” adds Bilodeau, “because we’re talking about serving recycled wastewater to people.”
Even though we are drinking the super-clean water out of the facility, the liquid will actually head back underground. Some of it will travel in pipes to the coastline of the Pacific Ocean where it will serve as a buffer to keep the salty water out of the coastal aquifer. Most of it will zoom 15 miles in pipelines to the city of Anaheim, where it will create lakes to percolate down into the aquifer and replenish the water that people drink in the county. “It’s the one that’s consistent, because we can control it,” says Bilodeau. “And that’s a big reason why we invested in recycled water so heavily.”
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The big drawback to this system is that making water – instead of sucking it from the ground – takes a huge amount of energy and manpower. The system consumes 17 megawatts of electricity and has a monthly electricity bill of $2.5m (£1.85m), while to run the place takes 26 operators.
But the technology also offers some control over an increasingly climate-changed future: Bilodeau says the team estimates several years ahead in terms of what they think their water needs will be and what the water sources will be. “That’s one of the main reasons why we developed this,” he adds. “Because we wanted to sort of diversify our supply portfolio.”
Some places are looking to the oceans for drinking water, but wastewater is more cost-effective as a source of water, Bilodeau says, because there are fewer salts in wastewater than sea water. That makes the energy costs of cleaning the water about half of what it would be to desalinate.
The model is increasingly being used in other water-scarce regions in the US. Los Angeles County is building a water recycling project in the San Fernando Valley to produce 20m gallons a day. Instead of sending treated wastewater out to sea, it will be cleaned for drinking water, just like in Orange County. There are also projects starting in Utah, Texas and Colorado.
California’s State Water Resources Control Board approved regulations for direct potable reuse in October 2024, which allow purified water to go directly into drinking water systems instead of being mixed in with other water sources. The technology in the treatment process allows for the water to be even cleaner than most drinking water.
The Orange County model has won awards, including a Guinness World Records title for the most wastewater recycled to drinking water in 24 hours on 16 February 2018. But the best praise is the public support for the water, says Bilodeau – and the economic argument behind it. “It’s now cheaper to make our own water than to buy imported water, or to clean sea water,” he says.