Chlorine demand
When chlorine and chlorine compounds are added to a water source, it purifies the water by damaging the cell structure of bacterial pollutants, thereby destroying them. The amount of chlorine needed to do this is called the chlorine demand of the water. The chlorine demand varies with the amount of impurities in the water and therefore the chlorine demand of a water source will vary as the quality of the water varies. Chlorine and chlorine compounds are consumed by inorganic and organic matters present in water before any disinfection is achieved.
