Water Towers

ithout any effort, Doug Smiley poured a glass of water from the fountain. The controlled flow of the water slipped with ease into the glass and slowly crawled over the ice. Within seconds, the glass was full.

Smiley does not work at any ordinary bar, and the water did not have an ordinary journey. He works at Windows on the World, atop the World Trade Center, where water for the bar, bathrooms and sinks has to be moved through a maze of pipes and pumps all the way up the tower’s 107 floors, totaling 1,358 feet.

One of four pumps that moves water up Tower One.

"It’s amazing to think
that we can move water up 1,300 feet," says Bill Hamann, the general maintenance supervisor in charge of the World Trade Center.

Hamann says that water for the towers is moved up the building through
a series of pumps at various levels. There are a total of 12 pumps situated throughout each tower. Four are located in the basement, four on the 41^st floor and four on the 75^th floor.

he pumps in the basement move the water at 250 pounds per square inch, or psi, enough pressure to get the water up to the next pump station. By the time the water reaches the next pumping station, the pressure has dropped to 29 psi.

So on the 41^st floor, the next station acts like a relay runner, taking the baton and pumping the water to the 75^th floor, again starting out at 250 psi.

Hamann says that if the building only relied on one set of pumps to overcome its massive height, then the initial amount of pressure needed would have to be around 640 psi.

"Can you imagine a bathroom on the 10^th floor with 500 pounds [of pressure] behind a pipe?" asks Hamann. "God forbid anything bad happens."

At any given moment, two or three of the four pumps are running. Sensors throughout the building’s pipes detect water demand by change in pressure values.

For example, Hamann says that at around 5 p.m. when the offices start closing there is an increased use of water in the bathrooms. Water pressure drops throughout the building. The pumps detect this drop in pressure and speed up to compensate.

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