Yes, they all have roof tanks (explains the tops of the Empire State
Building and the Chrysler Building). And yes, fire protection is the over
arching reason for why a tank is needed (this was changed just a few years
ago for new construction). See:
http://www.jrn.columbia.edu/studentw...hane-Tanks.txt
--
Peace,
BobJ

wrote in message
oups.com...

Speedy Jim wrote:
wrote:

I find it hard to believe that all tall buildings in NYC rely soley on
gravity water tanks. As has already been pointed out, the upper floors
would have little water pressure. This would seem to be a very poor
and impractical system. For example, how big of a tank would it take
to supply an 80 story building and what is the big advantage? A pump
has to get it up there to begin with. The only purpose I can see is
that there would be some supply to deal with a fire that would not
require electric service, pump, etc, but it would seem from a practical
standpoint, that supply isn't gonna be capable of doing much. It would
seem a far better approach would be to have a secure and power backed
up water pump system.


The City's water is fed from Croton (uphill) by gravity.
Almost none of the water is pumped .

Where it comes from has nothing to do with how you then supply it to a
60 story building.




http://www.nyc.gov/html/dep/html/history.html

http://www.fno.org/exhibits/WT/nd.html

http://people.howstuffworks.com/water.htm
Scroll down to bottom pic.


No question there are many water tanks on roofs in NYC. But, I always
see them on the older buildings, many looking like they have been there
for 75 years. Either they are hidden inside new skyscrapers, or
they have newer systems that no longer require tanks. My point is if
anyone is really sure that this is still what is being done today with
modern 60 or 80 story buildings.



OP may be stuck. Condo owners can't make changes
to the building willy nilly. Condo board *might*
consider an expensive upgrade to the building,
but likely will respond that this is how it is
in NYC.

Jim