Chemicals are then added to kill bacteria and strengthen teeth. An additional chemical, called alum, is also added. Alum is important because it causes tiny particles in the water to stick together. When enough particles stick together, the mass becomes too heavy to float and sinks to the bottom. The clear water on top is filtered and chlorine is added.
Chlorine kills any remaining bacteria left in the water.
Chlorinated water is then stored in tanks until it is used. Look around town, and you will see water towers all over the place. Machines pump the water all the way up to the top of these towers. Through a series of pipes, your house is connected to one of these towers. Once used, waste water run down your drains and into septic tanks or sewer systems.