The Wisdom of Water Towers

Why do water towers exist? You pump water up into the tower, only to have it come back down before it goes to its destination. Why not save the up-down circuit and just pump straight to the destination?

This question arose a week ago on my family’s annual summer visit to a small town amid the Illinois cornfields. Out there all the towns have water towers. Here is why.

Towns have pumping stations that can pump water directly to homes and businesses. However, demand for water is not constant. Overnight water use is low, but demand peaks in the morning when people are showering and starting their days. Building a pumping station to handle the peak demand is inefficient because the pumping station would only use a small fraction of its capacity most of the day.

Enter the water tower. It allows a town to build a pumping station that handles only the average daily demand, using the water tower as a cache. When demand is low, such as overnight, the pumping station fills the tower. When peak demand occurs in the morning, the tower releases water. Gravity acts as a virtual pump, allowing the tower to augment the actual pumping station. (The water tower can also be a temporary substitute for the pumping station in case of maintenance or a power failure.)

Water towers are prominent features of midwest towns because the geography is flat. The only way to elevate the water to the necessary height is to use a tower. In more varied terrain, the equivalent of a water tower is a big tank on a hill. In an urban downtown with skyscrapers, tanks may be on the roofs.

Whatever the location, an elevated cache of water is a simple, effective idea.