Gazing out over the New York City skyline, you can see the relics of a bygone era – rooftop water towers.  The water towers came into widespread use in the late 1800s as the city built up and the water mains could not keep up with the requirements of the ever-taller buildings. Like many of the 100 year-old public water mains, these rooftop water towers provide water to millions of New Yorkers. But unlike the public water mains, they are rarely cleaned or inspected and regulations governing the water tanks are rarely enforced.

Often there are thick layers of muddy sediment at the bottom of the tanks and layers of pigeon droppings in the crawl space between the roof and the tank cover. Tank cleaning companies have hundreds of stories of finding dead birds and mice. One cleaner even discovered a homeless person living in the space in between the tank cover and the roof!

The New York Times recently sampled the water from roof top water towers from 12 buildings in Manhattan, Queens and Brooklyn. They found E. coli, a microbe carried in the feces of mammals and birds, in 5 tanks and coliform, a bacterium that can predict the presence of disease-causing viruses, bacteria and parasites, in 8 tanks. According to state and federal standards, a positive result for either E. coli or coliform means the water is not fit for human consumption.

While the positive results came from the bottoms of the tanks, below the pipe that feeds the building’s water taps, public health experts say the contamination is still a concern as the water circulates throughout the inside of the tanks. One expert, Dr. Stephen C. Edberg, a public health microbiologist at Yale University who invented the now-standard test for bacterial contamination in drinking water, was so alarmed by the results that he alerted the New York City Department of Health and Mental Hygiene, the department which has oversight over the tanks.

New York City’s water system originates at 19 protected lakes and reservoirs in upstate New York and is thought to provide the finest tap water of any city in the world. But the vast system of safeguards protecting the water supply ends at the residential building. It is up to the building owner to ensure the building’s tank is cleaned, inspected and tested for bacteria annually, as required by the city’s building and health codes. However, New York City’s own surveys suggest than 60% of owners do not comply and the city does not enforce the codes.

Another concern is the use of Sea Goin’ Poxy Putty, which is not approved for drinking water, to caulk leaks in the wood tanks. The epoxy is a bisphenol A-based polymer used by at least 2 of the 3 major tank installation businesses in New York City.  The Department of Health and Mental Hygiene has said it does not necessarily matter that the epoxy was not certified for drinking water as most epoxy curing agents become inert once cured and therefore would not be expected to impact the water quality. Bisphenol A has been found to cause negative health effects in animal studies as it is an endocrine disruptor which can mimic estrogen.

If 60% of building owners are not regularly cleaning and testing the building’s water towers, what are you really drinking? Our suggestion to ensure your office is drinking clean water and not pigeon droppings? Bottleless water coolers with state-of-the-art filtration.