Roof Tanks 101 Construction, Maintenance & Repair

Rooftop water tanks are such a common sight atop New York City’s residential buildings that they often blend right into the cityscape. But these overlooked structures are an essential part of many buildings’ plumbing systems, providing water not only for daily use, but also for fire-suppressing sprinkler systems.

Tanks for the Memories

Around the turn of the 20th Century, builders in New York City wanted to build structures larger and higher, but the municipal water lines at the time did not have enough pressure to get water up more than five or six stories. It wasn't until a series of disastrous sweatshop fires killed scores of people working in the city's garment industry that city officials cracked down on builders and building owners, mandating stricter fire safety systems in commercial and residential buildings. Among the changes was the city’s requirement that buildings install and maintain sprinkler systems. The new safety codes made the issue of weak water pressure above the fifth floor more than just an issue of comfort and convenience; it became a matter of life and death, and was a key driver in the development and spread of rooftop water tanks.

There are very few companies in the city that handle the maintenance and construction of these mini-reservoirs, and all of the players know each other, and in some cases are blood relatives. In fact, depending on who you talk to in the roof tank business in New York City, you just may be talking to a direct descendant of one of the city's original roof tank builders. 

“I guess my great-great-grandfather, Harris Rosenwach, had the brilliant idea of putting a water tank on the roof,” says Henry Rosenwach, vice-president of Rosenwach Tank Co. Inc., based in Long Island City. “He bought a wine barrel company for $55 and it turned into Rosenwach.”

Wood or Metal?

While all roof tanks are similar, they are not all the same. There are two basic types: those that are made of wooden planks, and those made of sheet metal. Both types of tank are generally built on-site, though often, some prefabrication is done in the tank company’s shop.


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