jueves, 17 de abril de 2014

Inside New York City's Water Towers

Rooftop water towers are the primary source of drinking water for many New Yorkers, yet frequently they are poorly maintained, and present a potential health hazard.

Self-study activity:
Watch the video and answer the questions below about it.

The activity is suitable for intermediate 2 students.

1 How many water tanks on rooftops are there in New York?
2 How many of the tested tanks were positive for coliform bacteria and e-coli?
3 What is the source of e-coli?
4 What can you find in a tank in a deteriorated condition?
5 How often should tanks be revised by law?
6 What does 60% refer to?
7 What is the problem if part of a tank is contaminated?

To check your answers, you can read the transcript below.

Pisa has the Leaning Tower, Paris has the Eiffel Tower and New York has the water tower.
This is Frank Runyeon for The New York Times. There are ten to twenty thousand water tanks on rooftops across New York City. They are the primary source of drinking water for many city-dwellers, and yet the tanks are breeding grounds for bacteria and regulation of them is rarely enforced.

If part of my drinking water came from this, they would certainly change the way I drink water in the city of New York. Nothing to do with the municipal water supply, it’s to do with the tank.
The Times tested 14 tanks in 12 buildings in Manhattan, Brooklyn and Queens. Eight of the tank samples were positive for coliform bacteria and five had e-coli. The Health Department, which is responsible for ensuring that building owners inspect and test their tanks for bacteria refused our on-camera interview request, though an official told us that they are satisfied with the inspection requirements as they are right now.
The Doctor Stephen Edberg a leading medical and public health microbiologist who invented Colilert, one of the world’s most widely used tests for bacteria, says there is cause for concern.
E-coli has only one source. It is only there because some animal is defecating in that place, it’s the only way it gets there.
You have a bunch of two-by-fours, that get built up here as framework.
Stephen Silver is a third-generation tank man with American Pipe and Tank.
When the roof on the tank is in deteriorating condition and is open to the atmosphere, you have dust, dirt, pigeons, garbage, we’ve seen people living in roof tanks, you see mice and vermin in the roof tanks, and this is for the most part people’s drinking water that the people in the building don’t even know about.
New York City’s water is gravity fed from reservoirs upstate but this aquaduct system can only deliver water up to six stories so to provide water pressure to the upper floors, water is pumped from the basement to a roof top tank before draining directly into taps.
Water tanks can be exposed to the elements for up to fifty years, so to keep them in working order they need to be maintained.
New York City requires that these tanks are cleaned and disinfected a minimum of once a year, because this is a building’s primary drinking water source, so to prevent algae and bacteria from flourishing which would… under normal conditions you have a tank of water that is baking out in the sunshine all summer long you gonna get things growing in the tank.
We had the chance to drop our camera into a tank on a building above Time Square. We can see a layer of sediment that had built up at the bottom. This is a common site in water tanks around the City. Sediment should be flushed out every year.
It’s so inexpensive to maintain the code by cleaning your water tank and taking a water sample.
Cleaning only costs a few hundred dollars, but the problem is most of New York City’s water tanks aren’t cleaned every year, as required by law. A city survey of one hundred buildings showed that nearly 60% per cent did not comply.
It has been a problem. There has been a less than adequate compliance in my view. But we need buildings to step it up, we need to ensure that they are doing what they are required to do under the law.
The DEP is largely responsible for the city’s water, until it gets to individual buildings, and then it’s up to the landlords to maintain water quality. When tank companies are called to clean a water tank, they drain the tank, scrub the wood inside and add the disinfectant like Clorox bleach to finish the job. It’s also standard practice for them to take a water sample to test for bacteria. We took a sample from this tank just before it was cleaned. We took it to a lab for an independent analysis.
So the fact that the sample is yellow means it’s positive for coliform. And once it’s positive for coliform we put the UV light on it and if it fluoresces it is positive for e-coli.
So what it does mean that it’s positive for bacteria and e-coli?
It means at least from where the sample is collected it’s not fit for human consumption.
The Health Department says that the contamination the New York Times found in samples from the bottom of the water tank would not normally enter the water supply because drinking water exits through a pipe near the middle of the tank. The experts we spoke with disagreed.
In most of the world, water is stored in large vessels and the problem is that if any part of the tank gets contaminated, all of it is contaminated.
So if you have sediment in the bottom of a water tank, then whatever is in the sediment is going to get in the water supply.
Most likely, yeah, no hesitation.
Ok, even if it’s just, you know, at the very bottom of the tank can come up from the middle?
Yes, correct.
But with all these potential contaminants, why don’t we see more people getting sick?
It’s a very hard… to a population as large and dense as New York to ascertain even reasonably large illness outbreaks. You’d literally have to have entire apartment buildings getting sick at the same time. It disappeared, but they are there.
Despite billions of dollars spent to protect New York’s drinking water, the delivery system has a weak spot: the thousands of unmaintained, untested and forgotten water tanks.