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San Diego Learns How to Recycle Water

Above: San Diego's North City Water Reclamation Plant (NCWRP) is the first large-scale water reclamation plant in San Diego's history and part of the single largest sewerage system expansion in the area. This facility can treat up to 30 million gallons of wastewater per day, which is generated by northern San Diego communities.

Audio

Aired 6/25/09

The ultimate solution to California's water dilemma will draw on many sources. And one of them will be the supply of water we currently throw away. The water that goes down the drain, and down the toilet, can be reused. But finding the best way for San Diego to recycle is a technical and political question.

KPBS Special Report

H2NO: San Diego Going Dry

— The ultimate solution to California's water dilemma will draw on many sources. And one of them will be the supply of water we currently throw away. The water that goes down the drain, and down the toilet, can be reused. But finding the best way for San Diego to recycle is a technical and political question.

Recycling wastewater is nothing new. It's common and often unavoidable. Alan Rimer is a water reuse specialist with the firm Black and Veatch. He says wastewater reuse has taken many forms.

"I grew up in Pittsburgh Pennsylvania," he says. "And when I flushed my toilet, it went into the Ohio River with some treatment, and Cincinnati drank that water after taking it out of riverbank wells and treating it. And that's what we call indirect potable reuse."

To water reuse experts, San Diego is famous for the expression "toilet to tap." It arose about ten years ago when the city's first effort to reuse wastewater as potable water did a political crash and burn. But the reality of today's water shortage has put wastewater recycling back on the table. That's why San Diego is embarking on a plan to test a system for "reservoir augmentation." Wastewater will be purified to an advanced level so it could be piped to the San Vicente Resevoir, where it would become part of San Diego's supply of drinking water.

Marsi Steirer, with the San Diego Public Utilities Department, says, for now, the goal is test some new equipment at the North City Water Reclamation Plant.

"Basically what we're constructing as a temporary plant is a one million gallon a day advanced water treatment facility," she says.

The north city plant currently treats about nine million gallons of wastewater every day that's reused, mainly for irrigation. This kind of reuse requires a dual delivery system, since the North City plant doesn't currently treat its recycled water to the level of drinking water. The non-potable water flows through purple pipes to golf courses, parks and freeway medians. But the North City plant recycles less than half of what it could, due to a very limited distribution system.

Mixing highly treated wastewater with a city's drinking water supply, reservoir augmentation, is what they already do in part of Northern Virginia. Chuck Boepple is executive director of the Upper Occoquan service authority. He says his plant's wastewater is treated and discharged into the historic creek called Bull Run. That leads to a reservoir that provides drinking water for a million people in suburban Washington D.C. Boepple adds the water he puts in Bull Run is very clean.

"Our effluent, as a matter of fact, meets drinking water standards. Every parameter that EPA has on maximum contaminant levels for drinking water… we're beneath those levels," he says.

So why does Occoquan put safe drinking water in the reservoir where it'll just get dirty and need to be treated again? Beopple says doing a system where water really goes straight from toilet and tub to treatment to tap is still unacceptable to the public. Maybe so. But the water San Diego draws from the Colorado River contains lightly treated wastewater Las Vegas dumps into Lake Mead. Some say that the water people in New Orleans drink, that comes from the Mississippi River, has already been through about nine sets of human intestines.

Rick Gersberg is a public health professor at San Diego state, and he's on an advisory task force for the San Diego water recycling project. He says scientists can talk all they want to about actual health risks of recycled, drinking water. But what the public perceives as sanitary, is just as meaningful.

"Maybe a scientist would say 'Well, you know, risk is just the numbers we calculate.' But if you're dealing with risk and you're expecting to communicate and inform and have acceptance of a certain project, then that strictly science opinion is not the way it happens," says Gersberg.

Reusing wastewater has a political price and it has a monetary price. If the San Diego water recycling project becomes reservoir augmentation, it'll require a permanent treatment facility and a pipeline. The total cost would be at least $237 million.

Comments

Avatar for user 'smileydoh'

smileydoh | June 25, 2009 at 8:48 a.m. ― 5 years, 4 months ago

The idea of being able to "treat and serve" is an alternative to building a big and expensive recycled water system in San Diego. With San Diego being awarded an EPA waiver to continue discharging (wasting) 175 MGD of primary effluent to the sea from Point Loma, I see that San Diego has a strategy to avoid or postpone the cost of a recycled water system. Many sewage authorities north and south of San Diego, have bitten the bullet, and built recycled water pipeline systems. I believe the current drought, which could last many more years, makes it more imperative that San Diego do something now to recover the 175 MGD. Smileydoh

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Avatar for user 'WaterGirl'

WaterGirl | June 25, 2009 at 10:18 a.m. ― 5 years, 4 months ago

Water is a limited resource. Global demand is growing. Look at Singapore and Australia and the constrained resources they have. Singapore will have roughly 30 percent of their water coming from recycled use very soon.

We should be learning from the lessons others have learned and get over ourselves. It wouldn't be legal to put it in the tap if it didn't meet the same, high standards regular fresh water supplies have to meet.

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Avatar for user 'Jack'

Jack | June 27, 2009 at 7:25 a.m. ― 5 years, 4 months ago

WaterGirl said "Singapore will have roughly 30 percent of their water coming from recycled use very soon."

This is incorrect. Singapore currently recycles a maximum of 1% for potable use. They have no plans to increase this to 30%. Singapore also has the largest seawater desalination plant in South East Asia.

Australia currently has no example of planned potable reuse. Brisbane does not currently use recycled water in the drinking water supply. This may occur once the combined dam levels reach 40%, however, they are currently at 75%. Sydney, Melbourne, Adelaide, Perth and the Gold Coast are all building or have completed seawater desalination plants.

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