They're a familiar scene dotting the city skyline — sleekly conical yet distinctly old-world — but just how much do you know about how water towers work, why we still use them and exactly how safe the tanks where we store our drinking water really are?
The municipal water mains of New York City provide enough pressure to lift water roughly six stories up in the air. As turn-of-the-century buildings grew taller and taller, so did the demand for water at higher elevations. The concept of the water tower is simple: an elevated tank is filled by an electric pump in the building's basement, and the force of gravity on that heavy volume of water creates the pressure needed to distribute water to each floor.
Water towers were traditionally constructed from cedar planks bound together by circular steel bands. These days, some new tanks are made of steel but surprisingly, bloated cedar is an incredibly water-tight (not to mention much lighter and cheaper) barrier and thus frequently still in use today. In fact, not much at all has changed about water tanks in over 100 years. Many new buildings are now built with more powerful basement pumps that negate the need for hydrostatic pressure, but roughly 17,000 are still used in older New York City buildings today.
So who exactly is looking after your building's water? While New York City often brags about having the best drinking water in the country, for millions of residents, these holding tanks are their water's last stop before hitting their drinking glasses. According to the New York Times, the tanks are often neglected to the point that they may become hazardous. Though they should be cleaned yearly, those health regulations are rarely enforced. Untreated towers can collect layers of sludge and bacteria, and damaged covers can leave the water supply exposed to the open air and everything that comes with it: smog, debris and even birds or mice. When the Times tested 12 random buildings in three boroughs, they discovered coliform bacteria in eight and E. coli in five. Since the only possible source of E. coli is animal defecation, there's ample cause for concern that the towers aren't properly sealed.
The problem is regulation. Building owners are responsible for water tower maintenance, yet only 42 of 100 randomly inspected buildings could show they'd even tested their water for bacteria, much less regularly disinfected the tank. The health department claims that the Times' tests are inaccurate because they took samples from the bottom of the tank (where the debris collects) which is below the intake pipe that draws the water, but I think we can all agree that drinking straight from a tube of bacteria-laden water (regardless of which depth the bacterial outbreak occurs) isn't a great idea.
Why is no one addressing what seems to be an urgent public safety issue for millions of New Yorkers (and no doubt residents of other cities that use water towers)? We're not sure. It would cost $300,000 to set up a database to track water tower inspections, and $65,000 a year to maintain it, so that could have something to do with the lack of action. But it seems like a small price to pay for a much-needed update to this 100-year-old technology.