Sewers to Sinks
A drought-stricken California county has found a new source of water: its toilets
By Jonathan Parkinson
Water is so commonplace in countries like the US we sometimes take it for granted; it's safe, fresh and available at the flick of the wrist. But as drought in arid regions like northern China, eastern Australia, and the American Southwest intensifies and global warming alters weather patterns, clean water will grow more scarce for many; already, according to the UN, a billion people worldwide lack access to clean drinking water. The UN estimates that by 2025, two-thirds of the world’s population could face water shortage. Here in the US, the parched Southwest is already struggling: nearly eight years of drought have left reservoirs in the Colorado River basin almost half-empty, and in Northern California, 2008’s spring was the driest on record — with some researchers predicting still worse to come.
To meet the challenge, a growing number of cities are purifying wastewater to recharge groundwater or reservoirs, a process engineers call “indirect potable reuse” and skeptics refer to as “toilet-to-tap.” Among the early adopters are El Paso, Texas; Singapore; Windhoek, Namibia; and Fairfax County in Virginia. Other US cities considering or launching similar projects include Los Angeles, San Diego, and Miami-Dade County, which is scheduled to begin an operation in 2013 at an estimated cost of $350 million (that’s still cheaper and more energy-efficient than seawater desalination). Leading the way is Orange County, California.
Known more for its wealth than its filth, the county has a new state-of-the-art plant that opened in January. OCWD engineer Mehul Patel boasts of an 80-to-85 percent recovery rate; the plant produces some 70 million gallons of potable water a day — enough to meet the needs of nearly half a million thirsty Southern Californians.
Our tour of the filtration plant starts next to a row of concrete basins where Coca-Cola colored wastewater churns in the depths; solids have been removed, but this water is thick with muck. In a technique called microfiltration, pumps draw the wastewater through bundles of fibers shaped like ultra-slim drinking straws, with holes 1/300 the size of a human hair, trapping bacteria and dirt. Every fifteen minutes a blast of air flushes the dirt from the microfilter while the water passes to the next stage.
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Comments
what kind of sense does it make to flush our excrement into our drinking water supply in the first place? Among the obvious things human waste carries caffeine, nicotine, estrogens and other endocrine disruptors and a wide variety of pharmaceuticals into our rivers. COMPOSTING TOILETS...your time has come!
Posted by:nela |December 2, 2008 12:29 PM
Yes, that's all very nice, but not a word about pharmaceuticals and other molecules that are also difficult and expensive to remove. To omit mention of such obstacles to the safe reuse of water today is a disservice at best; a lie at worst. There must be FULL disclosure of ALL remaining contaminants in treated sewage water, and extensive research that proves longterm exposure to those levels is safe. Until that exists (it doesn't now), keep it the hell out of municipal supplies.
It's fine for watering lawns, where 50% of drinking water typically goes, so we can save truly clean and safe water in a more sensible way.
Adding treated sewage water to potable supplies is just the latest way of selling more water, rather than (heavens!) conserving. Profit for the supplier over safety for the public.
Beware.
Posted by:Florida osprey |December 2, 2008 11:48 PM
First, no matter where you live, if you think the water that comes from your tap now wasn't wastewater at one time then you're at best delusional. Consider that your long-term exposure study.
Second, those of us in Southern California spend lots of money and energy to tranport the water to meet our needs; to not use it again would be stupid and wasteful. Obviously we need to conserve, but conservation alone will only go so far when you have extremely limited resources to begin with.
While those of you in other parts of the country shun our innovation, we'll be having the last laugh when you're forced to eat your words and adopt it yourselves in the future.
Posted by:Laura |December 3, 2008 4:23 PM
Good comment by Florida osprey.
Yes, wonder what remains in the water:
The Netherlands is working on "membrane technology" which distinguishes between micro filtration and ultra filtration (required for removal of viruses).
Posted by:penta |December 14, 2008 2:15 PM
Of course there's going to be pharmaceuticals found in treated wastewater that will somehow get through. The difference is that in the US, only trace elements have been found and not at a level that poses a danger to human health.
Don't assume that the water you are drinking now is a sure bet. There is no such thing as a sure bet. And americans have got to stop with this neurotic obsession with perceived purity and sanitation. Every drinking water supply in the country is full of contaminants. Trace drugs are the least of the public's worries.
In fact, the treated water in OC is probably safer.
Posted by:savvysearch |December 19, 2008 6:19 AM