We have power failures all the time. Cable TV goes out fairly frequently. But the water in any city or suburb is always there.
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. In this edition of How Stuff Works we will look at how water towers work. A water tower is an incredibly simple device.