The pathogens like virus , bacteria , parasitic protozoa and worms are seen in domestic sewage . the polluted water have the pathogens of diseases like jaundice, cholera, typhoid, amoebiasis etc. the polluted water is unfit for drinking a, bathing and swimming etc. the heavy metal pollution of water will cause serious health problems,. The mercury metal poisoning cause minamata disease . the minamata disease reported in japan in 1952 , it is due to the use of fish captured from mercury contaminated water . by the bacterial action the mercury components are converted into methyl mercury, which is a toxic material. It can cause numbness of limbs, lips, and tongue, deafness, mental retardment . the cadmium metal contamination cause itai itai deasese . it is also known by the name touch ouch disease.  This is characterized by the painful bones joints. And cancer of lung and liver. The excess nitrates in drinking water is very dangerous for health . the excess nitrates in drinking water cause blue baby syndrome . the excess flurides in drinking water cause skeletal flurosis.  The arsenic pollution cause black foot diseases