I worked with the Red Cross (I was one of their Hams - NYC ARES) during the blackout.

The big need, the 1st night, was getting water to those walking home! Some building ownwers were nice enough to turn on their sillcocks to a snice steady stream so folks could fill their water bottles (part way into the trip, almost everyone had one - they went to the local deli and bought a bottle of water)

By about Midnight, all was quiet, and the next AM, the power started coming back on. I got called out to Brooklyn for a building with no water (remember folks, in NYC, basically, if you are above the 6th floor (lower if your in say, Washington Heights), your water is pumped by YOUR building - the water doesn't "Just flow"), but by the time we got there, the water was on

If the folks who LIVED in those 34 story buildings used their brains, there would be no problem - there is a VERY large water tank on the roof - if people didn't waste it, and only used it for drinking... I'll BET you, when the power first went off, lots of folks still showered etc - all the water on the roof went down the drain

In a "mid to high" end building, I would expect them to have a backup generator - but I know most don't (hey, why plan for a once every 20 year thing) and I KNOW a lot of the projects are lucky to have anything that works - even if the city did budget for a generator

Oh well - anyway, by Noon the next day, we were sitting around, with CASES of Gatoraide and Water, trying to give them to passers by, who looked at us and said "Dudes, the Blackout's been over for hours" - The team I was with at that time Was from Binghamton - they handed me a bag of Gatoraide powder to "put in the ARES supplies", and they took off for home - I waited for the re-supply truck to show, and told him to return the truck full of water bottles back to Central Stores - and I went home for a well deserved sleep (I did get about 3 hours at about 5am, but that was it)