At night, when demand normally falls to practically zero, the pump can make up the difference and refill the water tower. The output from the water treatment plant is clear, germ-free water. A high-lift pump pressurizes the water and sends it to the water system's primary feeder pipes. If the pump is producing more water than the water system needs, the excess flows automatically into the tank. If the community is demanding more water than the pump can supply, then water flows out of the tank to meet the need.
Water towers come in all shapes and sizes.
In a city, tall buildings often need to solve their own water pressure problems. Because the buildings are so tall, they often exceed the height that the city's water pressure can handle. Therefore a tall building will have its own pumps and its own water towers. During a fire, the water demand increases significantly and may greatly exceed the capacity of the pumps at the water plant. A water tower guarantees that there will be enough pressure to keep water flowing through the fire hydrants.