(TNS) -- Prune-dry California may soon be going down the toilet — for its drinking water.

The prospect of sewer water being treated and redirected back into faucets is the future of California if the water crisis continues, according to water managers throughout the state.

The challenge isn’t so much technological as it is cultural: Will people agree to use the water they once flushed?

Toilet-to-tap technology is already here. Two water districts in the Bay Area — the Dublin San Ramon Services District and the Santa Clara Valley Water District — are testing systems that filter sewer water and purify it to the point that it can be consumed by the public. Orange County has a system in place that recycles 100 million gallons of wastewater a day — enough to quench the thirst of 850,000 people — by treating it and injecting it into aquifers.

Experts say such recycling is the path California must take if it expects to have enough water for a growing population. Hundreds of billions of gallons of treated wastewater is now dumped into the Pacific. That’s water that could be used, according to resource managers, and municipal water districts across the state are looking into doing just that.

Water recycling “would greatly reduce the impact of the drought,” said Dan Gallagher, operations manager for the Dublin San Ramon district, which began providing recycled sewer water for residential irrigation last year and is pushing plans to treat the water until it is drinkable.

“People are going to do the dishes, wash clothes and go to the toilet no matter what,” Gallagher said. “The idea is, we can make use of that resource right here locally.”

Gray-water systems — in which homes and businesses are plumbed with purple piping that funnels used sink, bathtub and dishwashing water into the garden and toilet — have been around for a while. The technology that Gallagher and others are talking about, however, goes way beyond the reuse of water for irrigation or flushing.

Tough sell

The envisioned municipal recycling system would essentially squeeze out the crud on an industrial scale, purify what’s left and feed it right back to the public. Water resources officials estimate that, if fully implemented across the state, 1.1 million acre-feet of new water could be made available every year. An acre-foot is enough to supply a family of four for a year.

Peddling recycled water to that family may not be so easy.

“My wife and I were talking about that, and we’re kind of grossed out by it,” said Doug Havig, 56, of Pleasanton, who was filling up a 250-gallon drum of free irrigation water provided by the Dublin San Ramon district, which serves 140,000 people in Dublin, Pleasanton and San Ramon. “It’s just the thought that it comes through the sewer system that bothers me.”

Jose Carillo, 75, of Pleasanton, said he’s happy to use recycled water on his lawn, but would drink the stuff only as a last resort.

“If there was water from the store, I would drink that first,” he said. “But I would drink it if I had to and they assured me it was safe. I gotta survive some kind of way.”

Others, like Tom Kirkwood, said they are willing to accept recycled wastewater.

Getting used to the idea

“If it is run through all the purification systems, then I would drink it,” said Kirkwood, 71, one of up to 1,200 people a day who take advantage of free recycled wastewater provided at the Pleasanton sewage treatment plant. “I think we’re going to have to do something because water is a limited resource. It’s either drink that or drink more beer.”

The Dublin San Ramon district has an unhappy history with the excrement-to-agua concept. It spent $24.5 million to build a recycling system in the late 1990s. Problem was, when the locals got wind of it, they went bonkers.

“We were going through startup and there was a public outcry,” said Gallagher, recalling the intense opposition and threats of lawsuits. The idea had to be mothballed.

The general consensus among proponents is that people will overcome the “yuck factor” only if they understand the technology that can make sewer water usable.

A typical recycling plant takes what is called secondary treated water, meaning solids have been removed and it has been treated to the point that it meets federal standards for discharge into the ocean.

The water is then forced through a long series of tiny straw-like fibers called microfiltration. That cleans out all bacteria and most viruses. After that it is pumped through semi-permeable reverse osmosis membranes that block out any toxins that remain.

The water is then subjected to ultraviolet light and a hydrogen peroxide cleansing process that purifies it to the level of distilled water.

Orange County ahead

So far, there is only one large-scale recycling plant up and running. The Orange County Water District, which serves 2.4 million people, has recycled 70 million gallons a day since 2008. Its groundwater replenishment system was so well received that the district expanded production capacity this spring to 100 million gallons a day.

Districts throughout Southern California are copying it. The Metropolitan Water District is in talks with Los Angeles County sanitation districts to build a system that would reuse as much as 168,000 acre-feet of water a year. The proposed system, which would be the largest in the world, would cost an estimated $1 billion.

It is mostly because of the yuck factor that California does not allow the public to drink recycled water directly out of a treatment plant. Legislation has been introduced to change that, and the California Water Resources Control Board is expected to issue a report in December on the feasibility of such a system.

Until direct use is approved, recyclers will have to mix their product with groundwater. That’s what Orange County does.

South Bay recycling

The Northern California leader is the Santa Clara Valley Water District, which built a $72 million purification center last year to demonstrate to 2 million customers in 15 cities how a recycling system would work.

“We looked at everything, and this concept rose to the top,” said Pam John, the operations manager for the plant, which is the largest of its kind in Northern California. “It’s not as expensive as building a new reservoir.”

Recycled water now makes up about 5 percent of the 330,000 acre-feet of water used every year in the Santa Clara Valley district, John said. The plan is to increase the amount to 10 percent by 2022. The only cost-effective way to do that, John said, is to begin providing it as drinking water.

The district has run taste tests for visitors to its recycling center. “Most people say it tastes just like water,” John said.

A 2014 study by WateReuse, an organization that promotes alternative water supply development, found 62 percent of survey respondents supported using recycled water to augment the groundwater supply. A survey by the Bay Area Council this year found 88 percent in favor of expanding recycled water programs.

“The public is much more ready for it after four years of drought,” Gallagher said.

Cheaper than dams

“It’s clearly much less expensive water than building new dams, and clearly more reliable because it’s going to be there every year,” said Tom Stokely, the water policy analyst for the environmental group California Water Impact Network. “Why should people spend billions of dollars to send water to Southern California to flush it out into the ocean when they can recycle it? It’s really just common sense.”

After all, he and others insist, recycling water is what nature has been doing since the Earth cooled.

“All the water that we have on the Earth is all the water we are ever going to have and it’s all the water we’ve ever had, so we have to think about how we use it and how we can sustain it,” said Sue Stephenson, community affairs supervisor for the Dublin San Ramon Services District. “ I mean, you are drinking dinosaur pee right now, to be honest.”

©2015 the San Francisco Chronicle Distributed by Tribune Content Agency, LLC.

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