One man's sewage is another man's drinking water. As wastewater comes through this pipe, straw-like filters get rid of any contaminants wider than a human hair. That's just one step of the purification process.
One man's sewage is another man's drinking water. As wastewater comes through this pipe, straw-like filters get rid of any contaminants wider than a human hair. That's just one step of the purification process. Amy Standen/KQED
In California's Silicon Valley, there will soon be a new source of water for residents. That may not sound like big news, but the source of this water – while certainly high-tech — is raising some eyebrows.
With freshwater becoming more scarce in many parts of the country, the public may have to overcome its aversion to water recycling.
Ah, The Stench Of Drinking Water
If text could transmit odor, you'd know where this water is coming from.
"Well, we happen to be very close to a landfill," says Marty Grimes, a spokesman for the brand-new $68 million Silicon Valley Advanced Water Purification Center in San Jose.
There's also a wastewater treatment plant across the street. And that is where this water comes from: a place that smells a lot like a toilet.
Purple hydrants carry purified wastewater, mostly intended for landscaping.
Purple hydrants carry purified wastewater, mostly intended for landscaping. Amy Standen/KQED
"Wastewater is not necessarily a pretty business," says Grimes. "But let me tell you, the result of our plant is going to be pure, clean water."
It's a little unfair to linger on the unsavory sewage source. When this plant starts up later this year, it will be doing some of the most state-of-the-art water filtration in the country.
Naturally, that's what engineers here emphasize when they give tours.
"The water comes from the auto-strainers, where it's strained down to 300 microns," says Crystal Yezman, who works at the facility. One micron is one-thousandth of a millimeter, so 300 microns is about the size of a human hair.
That's step one — filtering out everything wider than a human hair.
Then, the water passes through filters that get rid of the tiniest of contaminants, like viruses or pharmaceuticals, by a process of reverse osmosis.
Finally, the water gets zapped by ultraviolet rays, which scramble the DNA of anything that might be living in it. This water is clean.
"The Department of Health has acknowledged that we are removing 99.99 percent of all pathogens," Yezman says.
If that's true, then the water is cleaner than snow melt, so to speak, and certainly as good as what people get from their kitchen sinks now.
Or, says Grimes, "it could be even better."
Erasing A Dirty Past
Despite how clean this water is, no one's going to drink it. Instead, it'll go into segregated pipes bound for landscaping.
But that may have to change one day because, like a lot of places in the West, water supplies here are drying up. Recycled water is the future — if enough people can be convinced that it's OK to drink.
"You have to break the memory, or the line of history, of the water," explains Brent Haddad of the University of California, Santa Cruz.
This is not an engineering challenge, he says. It's a psychological challenge. Water managers, he says, need to rewrite the history of the water to help people forget the part about sewage.
One way to do this is to take recycled water and put it back into a natural setting, like a river.
A "river is something that's comforting to people," says Haddad. "And we don't have to think anymore that it was passing through a city. We just begin the history of that water in the river itself."
Nine Years Of Convincing
This kind of water purification happens in nature every day. Just look at the Mississippi River — it's full of treated sewage water that people downstream clean and then drink.
And it's happening in Southern California, home to the largest potable water recycling facility in the world.
"We put it back into the ground, and then eventually it becomes part of the water supply," says Mike Markus, general manager of the facility.
Instead of putting their water into a river, his district cleans treated sewage and then pumps it underground, where it mixes with other water. Then, they pump it back up and treat it all over again, before piping it to peoples' houses.
Even with this crazy, Rube Goldbergian system, getting the public to accept recycled water took lots of meetings.
Markus says he and his colleagues talked to almost anyone who would listen — local elected officials, the health and medical community, the Chamber of Commerce, schools, environmentalists, rotary groups.
"We talked to the Sons and Daughters of the American Revolution. And scouting troops," Markus adds. "Anyone who would want to hear or receive a presentation."
That whole process took nine years.
The irony, of course, is that when you put recycled water back into the ecosystem, it actually gets dirtier and has to be treated again. How does it feel to put that beautiful, clean water into a hole in the ground? "Frustrated," Markus says.
So, he reminds himself that winning people over to recycled sewage water is a process — one that's just beginning here in Silicon Valley.