From Sewage to Drinking Water

Posted in: US Water News, Water Technology
Tags: , ,

Purified water from the Orange County Groundwater Replenishment System. The system treats sewage to produce water that can be pumped back into the county’s extensive groundwater supplies. (Photo credit: Mark Greening, OCWD)

Article courtesy of  Bradley J. Fikes | April 18, 2015 | U-T San Diego | Shared as educational material

Potable water reuse or recycling — purifying wastewater so it can be used as drinking water — eliminates the need for a separate network of purple pipes. However, it also has faced fits and starts in this region because of the “yuck factor” and other reasons.

During the late 1990s, a proposal to super-scrub wastewater into potable water crumbled in San Diego city amid the public’s fear about quality control and public health. Critics of the idea called it “toilet to tap.”

In 2007, then-Mayor Jerry Sanders vetoed a City Council vote to move ahead with potable recycling, citing what he saw as its prohibitive price tag. The City Council overrode his veto, but the lack of mayoral support stymied the plan.

Times have changed sentiments in striking fashion.

Orange County showed the way for San Diego with a groundwater replenishment system that processes wastewater to yield fresh water that recharges groundwater aquifers. The system was first installed to provide a coastal barrier against intruding seawater, which would have rendered the groundwater undrinkable. But by recharging the aquifers, it also provides a renewable source of groundwater that can be treated for drinking water.

In January, Mayor Kevin Faulconer and some environmentalists formed a coalition to promote potable water recycling. Their name for the concept: the Pure Water Project. From each gallon of wastewater, the city envisions converting 80 percent into ultra-clean water and flushing the remaining 20 percent as waste.

The pitch is part of a complex request that needs clearances from federal and state regulators. The plan is to release the repurified water into reservoirs, to be treated again along with incoming fresh water. This plan is called “indirect potable reuse,” as opposed to direct potable reuse, in which repurified water is directly piped back to customers.

If all goes well, the city estimates that by 2035 it can produce 83 million gallons of drinkable water per day from the project. That would be about one-third of San Diego’s total potable water consumption by then.

Other water districts in the county are headed in the same direction.

In October, the Padre Dam Water District in Santee broke ground on a test project for a potable-reuse system that could eventually supply 15 percent of its drinking water.

The city of Escondido is exploring plans to produce up to 12 million gallons of potable water to add to Lake Dixon.

And a half-dozen other agencies are eyeing water purification initiatives, too.

Environmental activist Marco Gonzalez, an attorney for the Encinitas-based Coast Law Group, said potable recycling needs to be a regional effort to reach critical mass. He noted that wastewater that currently flows to the sea from the Oceanside, San Elijo and Point Loma outfalls could be captured for full recycling.

It would cost billions to change the existing infrastructure of pipes and processing plants so it can become compatible. San Diego city’s Pure Water Project alone is projected to drain about $3.5 billion from taxpayers’ wallets and purses.

“We have infrastructure that has been put in over a period of time, some of it we’re still paying on,” Gonzalez said.

Conservation

In 1990, San Diego County used an average of 235 gallons of potable water per person each day. Last year, the number was 161 gallons — a drop of 31 percent.

But under a new mandate from Gov. Jerry Brown, San Diegans and other Californians are being pushed to reduce even more.

Click here to read more about conservation.

Purple piping

Perhaps the most palatable way to introduce reclaimed water is to reserve it for non-potable uses, such as agricultural irrigation, outdoor landscaping and certain industrial applications. This partially treated non-potable wastewater is distributed through a network of pipes easily identifiable by their characteristic purple paint.

Click here to read more about purple pipe water.

Desalination

Starting this fall, a part of the region’s water will come directly from the ocean for the first time. That’s when the Poseidon desalination plant in Carlsbad is scheduled to become operational.

Click here to read more about desalination.

The art of persuasion

To save water and develop a new strategy, it’s not enough to adopt laws and pass mandates and send out the water cops. People have to be persuaded that cooperation benefits them and their community.

Click here to read more about the role of persuasion and public opinion in meeting our water challenges.

Looking ahead

San Diego County’s two main sources of water, the Colorado River and Northern California, are tapped out. But the Water Authority found a new source of water in Imperial Valley, achieved through paying farmers for water-conserving equipment and lining canals. The three agreements securing that water will bring about 180,000 acre-feet this year. By 2020, about 280,000 acre-feet are projected to be delivered, more than 30 percent of the Authority’s water supply.

Click here to learn about some options for the future.

Want to Donate?
Please contact us for gifts in kind - Mail your check to: P.O. Box 545934, Surfside, Fl 33154