For the first time since its inception, the Gulf Coast Water Authority has to replace a pump station to secure a vital supply of cooling water to big industrial facilities lined up along Galveston Bay, from the island to Texas City.

Seventy years of pumping day and night has left the station badly corroded in parts, with cracks creeping up brick walls built in 1948. This is the youngest of GCWA's pump stations - the oldest was built in 1908 - but this one has suffered the most strenuous use, feeding up to 45 million gallons of Brazos River water each day to coastal plants run by Dow Chemical Co., Marathon Petroleum Corp., Eastman Chemical Co. and Valero Energy.

Those customers can't go a minute without water, so engineers must replace the station and move the nine vintage pumps it houses without interrupting flow. To do this, the pumps will be disconnected and hooked back up one at a time. The project is estimated to cost $14 million.

"Quite frankly, people in the Houston area don't realize that the economy runs on water. Everything in the Ship Channel, all those refineries, petroleum plants," said Mike Howe, executive director of the Texas section of the American Water Works Association. "In the long run, we're looking at billions of dollars to maintain a system, and people don't realize how valuable it is to them."

Much of the country's water infrastructure was built in the first half of the 20th century and designed to run for 75 to 100 years, according to a 2012 AWWA report that estimated a $1 trillion investment nationwide over the next 25 years would be needed to fix aging pieces and catch up with a growing population.

The association has dubbed these times "the era of infrastructure replacement."

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In Texas City, GCWA district engineer James Vanderwater saunters into a control room and switches on a pump. Outside, water spews from the bottom of a 3-foot-wide pipe.

"That's what happens when you have corrosion. We tried wrapping it, but that didn't work," he said. "This pump we try not to use. You can see why."

Another pump recently had to be lifted by crane so a worker could crawl inside the pipe it feeds and epoxy a curved metal plate over a leak on the inside.

"That's becoming more and more frequent," Vanderwater said.

Like the owner of a used car, the water authority had to decide when to halt the repairs and consider replacement. Officials hired LAN, an engineering firm with specialty in water infrastructure, to make the assessment.

"If they're going to do it, now is the time," said Melissa Mack, manager of the project for LAN.

On a lot behind the working station, the outline of the new building has been traced with spray paint, ready to be excavated several feet down to the level of the canal that runs about 80 miles from the Brazos River in Fort Bend County into Texas City, carrying virtually all the water that Galveston County consumes.

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One important part of the station doesn't need replacement: the pumps, each about 5 feet tall and 4 feet around. Six were installed inside in 1948 and another three were added outside in 1967. Now they'll be brought under one roof.

In spite of their age, the pumps persist thanks to a meticulous regimen of doing maintenance and replacing parts.

"We love our pumps," said Ivan Langford, general manager for GCWA. "It's like the ax you inherited from your great-grandfather. In that process, the handle was replaced three times and the ax head was replaced twice. That's like our pumps."

Once the new station is complete, each of the nine pumps will be hooked into new pipes and fired up before the next one is removed. That way, the flow of water continues unbroken and coastal refineries don't overheat.

The new station will also feature a new expanded system of filtration screens aimed at meeting federal regulations on the number of fish that get sucked into the system.

That also should help alleviate the flies and the stench of dead fish around the current water intake.

The renovation will also include a remake of the station's data and computing facility, where dresser-sized computers from 1992 currently sit in a line with blinking incandescent lights. That will include the nucleus of the plant, a 4-foot-tall cabinet filled with wires and switchboards dubbed the "programmable logic controller."

"This technology is not supported anymore, so we have to replace it," said Vanderwater, the engineer, gazing inside the facility. "It's going to be a little complicated, but it will work just fine."