Causes of water pollution: 

Water pollution is caused by natural and human sources.

• Natural sources of water pollution are due to erosion, landslides, gases, soil, minerals. 
• Human excreta, waste created by animals and other living organisms and rotting vegetation are also some causes. More than natural sources, water pollution is largely caused by human activities. 
• Humans pollute water through industrial, agricultural and cultural activities. Among these, industry is the worst culprit. 
• Industries produce a variety of waste products including industrial wastes, polluted water wastes, poisonous gases, chemical residuals, numerous heavy metals, dust, smoke etc.,
• Most of the industrial wastes are disposed off by running water. Consequently poisonous elements reach the lakes, river and other water bodies, which destroy them. 
• Reservoirs -They in turn destroy the bio-systems of the water. Major water polluting industries are leather, pulp and paper, textiles and chemicals. 
• Fertilizers, pesticides and insecticides, farm wastes and mineral particles from agricultural lands are washed down and end up in rivers, lakes and tanks. 
• The chemicals also infiltrate into the soil to reach the ground water.
• Addition of fertilizer increases the nitrate content of surface waters. 
• Religious and cultural activities like pilgrimages, fairs, tourism, immersi On of idols after pujas etc., also cause water pollution, 
• Urban activities such as improper sewage disposal also cause water pollution. 
• Effects of water pollution: Water pollutants adversely affect the health of humans, animals and aquatic life. 
• Water pollution is a source of various water borne diseases like diarrhoea, intestinal worms, hepatitis etc. 
• World health organization shows that about one fourth of the communicable diseases in India are disease water borne.