How do water towers operate?

Water towers, as far as infrastructure goes, are quite charming. In some cases, people convert them into homes when the city no longer requires them. The designers at Pop Chart Lab once crafted a visual tribute to New York City's water tower classification. But why is it necessary to store water so high up, hundreds of feet above the city?

The Importance of Height for Water Towers

Water towers are relatively basic machines. Clean, treated water is pumped into the tower, where it is stored in a massive tank that may hold a million or more gallons—enough to supply the city for a day. When the area demands water, pumps use gravity's force to create high water pressure. To harness gravity, the tower must be taller than the buildings it serves, ensuring it reaches the highest floors. For every extra foot in height, the water pressure increases by .43 pounds per square inch.

Here’s a simple diagram showing what a water tower system looks like:

Elevating water off the ground serves another crucial function for a city's infrastructure. It enables regions to use smaller water pumps.

Generally, a city's water demand varies throughout the day. Many people are using water in the morning for showers before work and school, but fewer are using it at 3 a.m. Without a water tower, the city would need to purchase a water pump large enough to meet the peak demand in the mornings, which would be underutilized during slower periods of the day, leading to wasted resources and extra costs.

Instead, cities can buy a pump just big enough to meet the average water demand for the day and let the water tower handle the excess demand during peak hours. When demand drops at night, the pump can replenish the water tower. Additionally, in the event of a power outage that disables the water pumps, the water tower can keep the supply flowing for at least 24 hours.

Take a Tour of a Water Tower

Take a look inside a water tower in Edmond, Oklahoma:

And also in Bloomington, Minnesota:

Here’s a 1-million-gallon water tank undergoing a cleaning:

The Importance of Water Tanks

Though water towers might seem like relics of the past, they remain highly relevant today. The Louisville Water Tower in Kentucky, built in 1860, holds the title of the oldest operational water tower in the United States and is still in use. In New York City, millions of residents continue to receive water from these towers, though it is one of the last major cities still relying on this system. Situated atop tall buildings, these water towers maintain water pressure even during power outages (especially in case of a fire).

And, of course, we cannot overlook the cultural significance of the water tower:

Every city deserves a towering civic monument to celebrate its beloved crop. Or perhaps a beverage decanter.