If It Ain't Broke Don't Fix It The Anatomy of Roof Tanks

As technology leaps forward, countless pieces of formerly indispensable equipment become obsolete, outdated, and replaced. In light of these technological advances, it’s interesting to think of the things that have not changed—inventions that function the same way today as they did when they were first introduced, having warded off replacement by newer, shinier incarnations. The short-list of timeless classics would have to include the Hula-Hoop, the Slinky…and the roof tank? Yes, the rooftop water tanks that dot the New York City skyline.

History Overhead

New York City’s first generation of roof tanks was built in the early 1900s to offer fire protection to the city’s taller buildings. According to Steven Silver of American Pump & Tank Lining Company in Manhattan, steam-driven pumps could only push water up a few floors, leaving the upper floors of skyscrapers with no real protection from fires. “New York City was really one of the first cities to go vertical, as far as skyscrapers go,” he says. “And back in the early 1900s—after some unfortunate fires and a lot of deaths in some of these higher buildings—the idea was to get some kind of [water] reserve on the upper floors.”

The New York City fire code is very stringent, says Andy Rosenwach, president of Rosenwach Tank Inc. in Long Island City. “One of the requirements for meeting that code is supplying a certain quantity of water on top [of buildings], as opposed to trying to design the building to have pressurized fire pumps and generators and other equipment… Anything over six stories requires either a constant pressure system or an artesian well on top of the building to gravity-feed down,” he says.

Over the past century, says David Hochhauser of Isseks Bros, Inc. in Manhattan, the design of roof tanks has not changed a whole lot, but nowadays they are getting larger. “Because of the new New York City fire code, tanks are being built much larger because they have to have the capacity [to serve] sprinkler systems. Whereas in the past a typical residential building would have a 10,000-gallon tank, nowadays we’re putting up 20,000- to 30,000-gallon tanks.”

How Do They Work?

The fact that roof tanks have not changed that much over the years is a testament to their incredibly effective design, which—in principle, at least—Is extremely simple.


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  • The Board of Directors of my building was told that the tank control sensor in the roof water tank needs replacing at a cost of $6,500, which includes a 10 year warranty against wear and tear. Does that sound reasonable?