Industries dealing with chemicals, pulp and paper, food processing, etc. produce waste material such as heavy metals or synthetic organic compounds. These reach water bodies either through direct discharge or by leaching from waste dumps. Among the heavy metals, cadmium, lead, mercury, copper, chromium etc., get into water.
The industrial waste mixed with water makes it poisonous and unhygienic. It may also cause various diseases in humans and animals, if consumed without treatment.