Rosenwach Tank Has Stayed In Business For 150 Years Doing Something That's Almost Obsolete

Rosenwach Tank

Photo: Yepoka Yeebo / Business Insider

Six workers are swinging axes, hauling timber and throwing around an arsenal of power tools perched high above an old building on Harlem’s 125th Street. With no scaffolding or supports, they’re a rare sight. Even more unusual: they’re building a wooden water tank.

This is the legendary construction team of Rosenwach Tank. They can put up a 10,000-gallon wooden water tank in less than half a day. You’ve seen their work. 

Click here to see the Rosenwach Tank crew at work >
The wooden tanks on top of buildings all over the city are a quirk of New York’s infrastructure. Wooden water tanks were vital in the early twentieth century, as the city grew skyward. They’re the way many of the city’s older buildings get their water supply, and have enough water stored to feed the sprinklers if there’s a fire. They use wood because just three inches of wood insulate the tank as well as 24 inches of concrete would.

Rosenwach is the last company to make them in the city. It has been in business for almost 150 years doing something that’s now almost obsolete.

The company is still around because while their market is disappearing, it’s disappearing very slowly.

“We’re in a dying business,” said Andrew Rosenwach, whose great-grandfather started the company. “When I was looking at joining, my father told me ‘If you join the family business and they stop putting tanks up, you’ll have enough business taking the tanks down,'” he said. 

Companies in this position have a choice to make, say strategists. They can retreat into their niche and watch the clock wind down. Or, they can fight, by moving their business away from the obsolete.

Andrew Rosenwach has chosen to fight.

Essentially The Same Since 1865

As long as New York is still a city of old buildings, Rosenwach will be in business. While wood is still lighter than concrete, and a better insulator than steel, they’ll be putting wood tanks on newer buildings. But those days are numbered.

Founded in about 1865, Rosenwach Tank is an old school business. They make their own brass pipe: if they didn’t, it would cost $1200 a foot. They even mill their own wood in the company’s original Brooklyn workshop.

“It’s a unique job. Only three of us do it in a city of 10 million,” said Ken Lewis, who runs the Williamsburg workshop.  Lewis has been at Rosenwach for 35 years, which, he acknowledged, was rare: “That’s just the way this company is,” he said.

“We survive on our own ingenuity and quality. That takes time,” said Andrew Rosenwach.

Surviving On Ingenuity, Timber And Steel

“We’re constantly reinventing ourselves,” said Andrew Rosenwach, taking us on a tour of a workshop in Queens. Rosenwach focused on using every facet of the their expertise Pointing to a massive bench made for a Staten Island park, he explained that they wanted to keep the wood shop busy through the year, so they spun-off a company that makes furniture and decks for parks and gardens.

With their expertise working on old buildings, they spun off another company that restores old facades. To keep the tank team busy during the winter, they fix sprinkler systems and service and build air conditioning cooling towers. Each wave of innovation meant serious investment.

“We survive on our own ingenuity and quality. That takes time,” said Rosenwach. “We’re not cutthroat,” but at the same time, “If you’re not up to speed with us, you’re not going to stay in business,” he added.

Right now, the only competition left is Isseks Brothers. The Manhattan-based firm is almost as old as Rosenwach but they moved production to a factory in Pennsylvania.

How Companies Go From Obsolete To Vital

Over decades, “This can go two ways,” said Professor Ron Adner, at the Tuck School of Business at Dartmouth. Some companies, like Crane — who make the paper dollar bills are printed on — and Remington — who make firearms— can stay on top by leading their niche. 

“Others move towards greater and greater diversification, like Colgate or Proctor & Gamble,” said Adner, author of  ‘The Wide Lens: A New Strategy for Innovation,’ which explores why great products and businesses fall into obscurity.

“They [Rosenwach] are in a decaying market,” said Adner. “The real challenge will be shifting the core.”

The problem is, wooden tanks still dominate Rosenwach’s business. The landscape furniture company, for example, keeps three or four men employed but it’s maybe 10 per cent of the company’s value.

“[Our] future is dominated by the tank business,” he said. But that has to change as quickly as the city’s skyline.

On a recent Saturday, the Rosenwach crew were up early dismantling the old tank, and preparing the frame for a new, 10,000 gallon water tank. Here, foreman CJ Adonis is standing on the iron frame the tank will sit on.

The six-man crew haul up a new section of the metal frame. They build between 100 and 200 tanks each year. The average tank costs about $55,000.

Ken Lewis explains how he mills the wood for the bottom of a tank. Lewis runs Rosenwach's Brooklyn workshop and has been at the company for 35 years.

The tanks are made just like barrels, with planks of wood held in place with nothing but metal bands.

Carpenter Ivan Suarez drives a forklift in front of a new tank, ready to be shipped out. Ivan joined Rosenwach about 27 years ago.

Sawdust on the floor of Rosenwach's Brooklyn workshop. The tanks are made from Canadian cedar wood, which doesn't have to be lined or specially treated.

The tanks can last up to 35 years before they need replacing.

The team does almost everything by hand, with an arsenal of tools. The process hasn't changed a great deal since the company was founded around 1865.

The Rosenwach team fit the last planks, finishing the sides of the tank. The tank is secured with metal bands, which are repeatedly tightened until the tank is almost water-tight. Water leaks through the cracks in the tank as it's filled, until the wood expands, closing up all the gaps.

A worker cuts the steel bands from the old tank into sections before they're scrapped.

The wood tank keeps the water cold in summer, and stops it freezing in winter.

Worker Atar Makdhoi drives the planks against the bottom of the tank with the butt of an axe.

Worker Philippe Martinez shuts off the water valve at the base of the pipe feeding the tank.

An average tank holds about 10,000 gallons of water; the largest tanks hold about 50,000 gallons.

Workers Atar Makdhoi and Philippe Martinez wind down. There are around 10,000 in New York City, and Rosenwach is responsible for over half of them.

Forman CJ Adonis, is on the roof of the tank as worker Marlon St. Hill tightens the nuts on the metal bands holding it all together.

Worker Eldon Nicholls is carrying rope and an extension cord as the team finishes up for the day. They'll be back in a couple of days to put the decorative conical roof on the tank.

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