Thursday, December 1, 2011

Rooftop Water Towers

Seen on rooftops all over the city, these water storage vessels last about 30 years. The yellow cedar wood strips are held together with steel bands, and the water inside swells the wood for a leak-proof fit. The wood insulates the water well enough to keep it from freezing in winter. Buildings taller than five stories need to have water pumped to the upper floors.

In the 19th century, NYC required that all buildings higher than six stories be equipped with a rooftop water tower. This was necessary to prevent the need for excessively high pressures at lower elevations, which could burst pipes. In modern times, the towers have become fashionable in some circles. As of 2006, the neighborhood of Tribeca requires water towers on all buildings, whether or not they are being used.

Two companies in New York build water towers, both of which are family businesses in operation since the 19th century. The original water tower builders were barrel makers who expanded their craft to meet a modern need as buildings in the city grew taller in height.

The rooftop water towers store 5,000-10,000 gallons of water until it is needed in the building below. The upper portion of water is skimmed off the top for everyday use while the water in the bottom of the tower is held in reserve to fight a fire. When the water drops below a certain level, a switch or  valve activates activate a pump or open a public water line to refill the water tower.