Swimming pool water must undergo treatment, in order to remain clear and clean, free from harmful substances, bacteria, viruses, algae and other pathogens and suitable for use by swimmers. Swimming pool water is treated by means of various purification steps .

The water is first transported from swimming pools to a water purification plant.In the water purification plant, it will flow through a hair removal filter ,which removes raw pollution, such as hairs, plasters and leaves, from water. After that, a flocculant is added, which causes smaller colloids to bind together. Colloids are visible floating particles of organic matter, such as skin tissue and textile fibers. This group of pollutants also concerns colloidal pollutants, such as saliva, soap remains, cosmetic products and skin fats. When these pollutants are abundant, they cause turbidity. Parameters that indicate the presence of undissolved particles are water turbidity and potassium permanganate (KMnO4) demand of the water. Potassium permaganate is used as an indicator of organic matter oxidation.Floating particles are removed from water in a sand filter. The sand filter is back flushed periodically. Finally, pollutants are discharged into the sewer.