I did say "low rise" building under say 5 stories. Ebven the lower floors of High Rise building use a pump for the tank, and feed from there. Often there is a hose bib on the building that is on city water pressure, and I can guarntee you in the boiler room somewhere is a feed that comes off city water. The hydrants out on the street WILL have water. You may have to carry it up, but the problem isn't GETTING water, but in moving it up.

Basically, if you live in a 4 story or less building in NYC, you won't have water problems - taller, you may/will. One of the interesting "jokes" is that the water pump in most buildings is NOT that large, as the tank acts as a buffer - the pump doesn't have to meet the instantanious need of the building, just the average sustained need, plus some safety factor

Funny story from 2003 - I was sent out to do Comms for the Red Cross - That night, we had lots of demand for bottled water from folks walking home, until around 11pm. The next afternoon, I was sent to one of those "buildings without water" - seem when the electric came on in the early AM, they were still complaining about "we have no water" (BTW the Burger King and the Super Market across the street were working, and the super had a hose bib open) - I got there (circa 2pm-ish) an the water crisis was over - seems the super went through the building and had folks turn off their faucets for an hour or so - to allow the tank on the roof to fill. Something like 90% of the apartments left a faucet on to "know when the water came back" - they were draining the water tank faster than the pump could fill it

So - I'll say agin - storing "emergency" water in NYC isn't a HUGE deal - if you can get to ground level, you will get NYC water, by pure gravity - the only problem is getting water from street level to your apartment - and you only need to store as much as "how often you want to climb the stairs"