The purpose of water treatment and purification is to improve the quality of water so that it is safe for human consumption, suitable for various industrial and commercial purposes, or meets some other specific need. Water treatment may involve any number of steps in order to achieve the desired outcome, such as removing impurities through filtration, disinfecting with chlorine or ozone, or adding minerals back into the water to make it more palatable. It's important to remember that not all water needs treatment - for example, rainwater collected from rooftops typically doesn't require any additional steps beyond collection and storage.

Water treatment and purification is used to improve the quality of water by removing contaminants. This can be done through a variety of methods, such as filtration, sedimentation, and disinfection. By removing these contaminants, the water becomes safer for human consumption and can also be used for other purposes, such as irrigation or industrial processes.