Water pressure is very reliable. A big reason for that level of reliability is the water tower. You see water towers everywhere, especially if you live in a flat area full of small towns. Each water system has one or more towers. A water tower is an incredibly simple device.
Water towers are tall to provide pressure.
The water tower must be tall enough to supply that level of pressure to all of the houses and businesses in the area of the tower. Therefore water towers are typically located on high ground, and they are tall enough to provide the necessary pressure. In hilly regions, a tower can sometimes be replaced by a simple tank located on the highest hill in the area. A water tower's tank is normally quite large. Typically a water tower's tank is sized to hold about a day's worth of water for the community served by the tower.