The process of cleaning water.

Water treatment, also referred to as water conditioning, can consist of adding or removing chemicals to change the properties of water. In water softening, for example, sodium ions are substituted for metallic ions that cause "hardness" thus reducing the scale-forming tendencies of water. Water purification on the other hand, always consists of removing undesirable impurities.

A process of cleaning water to make it suitable for drinking.

primary treatment mechanically removes solid matter Secondary treatment uses bacteria to break down dissolved organic matter. Tertiary treatment uses chemicals to remove additional contaminants.

Water treatment describes the processes used to make water more acceptable for a desired end-use. These can include use as drinking water, for use in industrial processes or to allow discharge into the environment without adverse ecological impact. These processes may be physical such as settlement, chemical such as disinfection or coagulation or biological such as lagooning, slow sand filtration or activated sludge.