By J.B. Smith

Tribune-Herald staff writer

Consider the pretzellike life cycle of the public water supply. Water is pumped from reservoirs and aquifers, treated to drinking standards and piped to people who spray it on their lawns.

Or it’s fouled in kitchens, toilets and showers, then transported many more miles to be treated again and dumped in the river.

This system may be sanitary and convenient, but it’s also wasteful in a state where growth is bumping up against limited water supply.

That’s why McLennan County cities are beginning to explore ways to squeeze the most out of every drop of water.

City of Hewitt officials, facing limitations on water supply and sewer capacity, are discussing the possibility of requiring “graywater” reuse systems in new homes. That means diverting water from washing machines and showers to separate plumbing that will irrigate the lawn.

Meanwhile, the Waco Metropolitan Area Regional Sewer System, which includes Waco and its suburbs, is planning to resell millions of gallons of treated wastewater for nonpotable water uses, starting with a coal-fired power plant now under construction in Riesel. Dynegy is expected to pay up to $750,000 a year for sewer effluent from the main WMARSS plant on the Brazos River.

WMARSS officials are considering spending up to $6 million next year to pipe water from the main sewer plant on the Brazos back upstream on Flat Creek to be used for golf courses or factories.

And the regional system is hoping in coming years to divert up to 600,000 gallons a day of treated sewer effluent from the proposed Bull Hide Creek plant near Lorena.

“What we’re doing and what Hewitt is looking at doing helps us meet our water demand through the state’s 2060 water planning horizon,” said Waco Assistant City Manager Wiley Stem. “We have to figure out ways to use water in a way that we can sustain it given our limited supply. That means we’re going to have to use water differently than how we use it now.”

Cut in consumer use

State water planners are counting on consumers to reduce their use of water in coming decades, partly by installing more efficient appliances and irrigation systems.

The State Legislature in 2003 also made it easier for consumers to use some of their water twice through graywater systems. State rules now allow homeowners to discharge up to 400 gallons a day of water from showers, baths, bathroom sinks and washing machines onto yards. The water has to be strained and cannot be allowed to pool. It can’t be sprayed on the lawn, and homeowners must be able to divert the graywater stream back into a sewer or septic system.

Officials with the Texas Commission on Environmental Quality and the city of Waco said they haven’t seen a rush of people installing such systems.

But Hewitt community services director Paul Holroyd said the city of Hewitt is considering requiring them in new homes, complete with a storage tank, a pump and separate plumbing. He estimated that the systems could cost about $2,000, though he said more research is needed.

He said the system would benefit Hewitt and individual homeowners. It would take strain off Hewitt’s city wells, especially in the peak summer months. It also would divert wastewater from sewer pipes and lift stations, which have been under strain. And in the long run, it would save residents money.

“We’re still in the headscratching stage,” Holroyd said. “The city council has discussed it some, but the staff will have to develop it before it goes to council for a decision. . . . I don’t know whether we’ll eventually adopt that kind of measure, but people today are much more environmentally conscious than in the past, and this is a good way to save money.”

He said he and most other Hewitt residents have concrete foundations, which are impractical to retrofit for graywater systems.

“If I could do it tomorrow at my house, I’d do it,” he said.

Eddie Wilcut, conservation manager for the San Antonio Water System, said he’s not aware of any cities in the U.S. that require dual plumbing for graywater, though it would be a good idea.

He said such a system might save a family of three about 120 gallons a day, which might not be enough to justify the expense of storing and pumping the water.

Still, he said plumbing new houses for graywater would be a forward-looking step in a state where water is becoming scarce.

“If we’re really serious as a state or a country, we need to start dual plumbing in every house we build today,” he said.

‘Purple pipe’ system

In the meantime, he said San Antonio has become a leader in water conservation through low-flow appliances and better irrigation practices. While its population has increased 50 percent since the 1980s, overall water consumption has remained steady in the city, which relies on limited groundwater supplies.

He said part of San Antonio’s conservation strategy was treating and reusing wastewater. The city installed a “purple pipe” system — the pipe color indicates that the water is nonpotable — to serve industrial and irrigation users and to keep the San Antonio River full. The water sells for one-fourth the cost of regular drinking water.

Waco also is awakening to the value of its treated effluent, said Stem, the Waco assistant city manager.

He said some cities are selling effluent for 70 percent of the cost of regular water, but he would like to sell it cheaper to maximize its use. He said the majority of the effluent from Bull Hide Creek could be sold to users in Lorena, Hewitt and other communities.

Meanwhile, engineers are studying the feasibility of adding a “purple pipe” system as part of a 2009 project to pipe sewage to the main WMARSS plant from Interstate 35 between Loop 340 and Sun Valley Boulevard.

The purple pipe carrying the treated effluent would parallel the main 42-inch-wide sewer interceptor line but would flow the opposite direction, from the sewer plant toward the Texas Central Industrial Park.

“If we can capture that water at the treatment plant, we’re really making the most efficient use of our water,” Stem said.

jbsmith@wacotrib.com

757-5752