Water tanks

New York City’s skyline is dotted with wooden water towers that are easy to mistake for vanishing relics of the bygone eras of seltzer bottles and street gas lamps.
But what many New Yorkers don’t realize is the towers are hardly antiques — in fact, most drink and bathe from the water stored in them every day.
“When I tell people what I do for a living, they can’t believe it is still done,” said Kenny Lewis, foreman of the Rosenwach Tank Co.’s wood shop in Williamsburg, Brooklyn, the only one like it in the city. “After people notice the tanks, they can’t believe how many there are.”
Most buildings in the city taller than six stories need some sort of water tower and pumping system to provide water pressure to tenants.
Rosenwach is one of two companies in the city that makes wood water towers. The other company is Isseks Brothers.
So why do people think wood water towers are relics of the past?
Because they look as though they are.
While many are more than 30 years old, even new ones look old because they are made of wood that isn’t painted or chemically treated (so as not to taint drinking water).Though the technology has become more efficient, the concept of gravity delivering water from a wood tank hasn’t changed in decades.
And while steel tanks are an option, they are more expensive, don’t provide as much insulation, require more maintenance and take longer to construct. The average wood tank holds 10,000 gallons of water and costs around $30,000. A steel tank of similar size could cost up to $120,000. But different buildings have their own specific needs.
“There are wood tanks, steel tanks, small tanks — hot, cold, round, square — it’s like a Dr. Seuss book,” said Andrew Rosenwach, the company’s fourth-generation owner.
Rosenwach estimates his company has about 10,000 tanks around the city, and can build up to 300 a year — though they’ve been suffering just like every one in the construction industry.
He said business should heat up with the weather. Every year they must clean natural sediment from the water off the bottom of the tank. More buildings have their maintenance done in the spring and summer, and if the tank is too leaky, a new one must be built.
With a crew of about six men, an old tank can be torn down and new one constructed in 24 hours, Rosenwach said. It takes two to three hours for pumps to fill them up.
“When you first set them up they leak, but when they fill [with water], the wood expands and becomes water tight,” Lewis said. “Then, it’s like a giant toilet. When people use water, the level goes down. A ballcock lets more in, and that water is pumped from the basement.”
Eventually the wood will rot though, which has kept the Rosenwachs working on the same buildings for generations. A tank can last 30-35 years depending on exposure to the elements. Rooftop tanks on the west side of Manhattan typically don’t last as long because they take more of a beating, Lewis said.“When we look at the skyline, we can tell which tanks are ours because they have tan roof covers and signature ‘R’ on the top,” Rosenwach said. “I’m always amazed what a vast amount of skyline we cover in such a small field.”

How the water tank works:
- A water tower is a simple device that uses gravity to provide water pressure.
- They provide water for domestic uses and fire supply.
- Most municipalities have tanks that can hold a day’s worth of water for their population.
- Many New York City buildings exceed the height the infrastructure’s water pressure can handle.
- Most structures taller than six stories need some sort of water tower and pump system of their own.
- Water is fed to buildings through pipes in the basement.
- Electric pumps push the water from the basement to roof.
- It takes 2-3 hours to fill the average 10,000-gallon tank.
- From the roof, gravity sends water to pipes throughout the building.
- As tenants use the water, the level in the tank goes down and, just like in a toilet, a ballcock lets more in

Is it a hothouse on the corner of this building's roof?