To climb any higher, the water needs help. That’s where the pump comes in, pushing water to the top of the building, where it sits in a reservoir, the familiar wooden water tank. Turn on the faucet and the water travels back down to you.

The physics don’t change, even for skyscrapers. People living in 50-story buildings “get their water the exact same way the old buildings do,” said David Hochhauser, who, with his brother and sister, owns Isseks Brothers, one of the city’s oldest water tank manufacturers.

Newer towers tend to hide their reservoirs inside and often use multiple tanks housed throughout the building so water can be pumped to the top in smaller increments. The new One World Trade Center has 16 water tanks, according to Mr. Hochhauser, whose company installed the tanks. At another Isseks installation, 217 West 57th, which will be the city’s tallest residential tower when it opens, 11 stainless-steel tanks will hold water.

New buildings aren’t the only ones with aesthetic reservations. Some of the city’s prewar gems, like the 27-story San Remo on the Upper West Side, built ornate structures to keep tanks out of view.