Answer: Water Pressurization

At first glance, it would be easy to assume that water towers exist to store water. They are, after all, giant above ground vessels filled with anywhere from tens of thousands to millions of gallons of water.

But whether you’re talking about a modest little water tower perched atop an apartment building in New York City or a giant municipal water tower, water storage is not the tower’s primary function (if water storage was the only goal, it would be significantly cheaper to build a reservoir).

The primary function of water towers is to pressurize water for distribution. Elevating the water high above the pipes that distribute it throughout the surrounding building or community ensures that hydrostatic pressure, driven by gravity, forces the water down and through the system.

The design helps keep the cost of water distribution lower for two reasons. First, it allows for centralization of pumping and pressurization, and decreases the number of pumping stations needed in the vicinity of the water tower. Second, it allows the water company to pump water up to the tower during off-peak energy times to decrease the expense of running the pumps.