I stand corrected. I was thinking only of the tanks on commercial and industrial buildings, not the ones on residential buildings. In NY, most residential buildings aren't required to have sprinklers, except probably in the basement and the cockloft, which is the space between the top-floor ceiling and the actual roof. ("Cockloft," a word that's inspired as many puerile architecture jokes as that element of water-pressure calculation, "feet of head.") In buildings like Jen's the tank is mostly for domestic water, which then feeds down by gravity instead of up by pump any time anyone needs some. Much more efficient. Though there's got to be a pump to get water to the tank, Jen, because that's a 15-story building and if we had the pressure in the street to do that we'd have Old Faithful right here in Manhattan. Rosenwach does make most of the tanks in NY, and Isseks Bros. the rest. Jewish immigrant carpenters, Mr. Rosenwach and the Messers Isseks, who saw an unfilled niche in turn-of-the-last-century New York as fire-suppression laws were being passed.

And Michael, as far as I'm concerned everybody should get Continuing Ed credits of some sort for reading this blog.

Now, for the Smart Blog Reader of the Week award. Can anyone (not including Warren and JL, who are in the biz) tell me how, after putting together these precut, fitted tongue-in-groove tanks, they keep them from leaking? Answer tomorrow; watch this space.