Water pollution is caused by organic and inorganic industrial wastes and effluents discharged into rivers. The main culprits are paper, pulp, chemical, textile and dyeing, petroleum refineries, tanneries and electroplating industries that let out dyes, detergents, acids, salts and heavy metals like lead and mercury, pesticides, fertilizers, synthetic chemicals with carbon, plastics and rubber, etc., into the water bodies. Fly ash, phospo-gypsum and iron and steel slags are the major solid wastes in India.