Water which we are drinking must be pure. Deseases spreaded through water causes serious problems: dissability and massive death, especialy of kids. This usually happens in less advanced countries, where there is low level of higiene. In result the pollution of water sources primarily transmitted to humans diseases such as typhoid, dysentery, cholera, hookworm disease.
Through the water can spread infectious jaundice, tularemia, water fever, brucellosis, poliomyelitis. Sometimes the water becomes a source of human infection and animal parasites - worms.
The quality of water is determined by the presence in it of chemical impurities that are used to discover all our senses: smell and sight. For example, microscopic substances of copper give to the water some turbidity and iron - redness.