Water occurs in most foods and as free fluid. Some two thirds of rain water returns to the atmosphere by evaporation, so there is a renewable commodity.

In organised societies, domestic drinking water, free from bacteria and other pollutants, is made available through a piped water system. Waste products, such as sewage should also be removed from the domestic scene by pipes and disposed of in a manner , safe for the population and the environment. Traditional lead pipes are a hazard and may leach lead into water, and therefore there is a vigorous policy to remove domestic lead piping.

World wide, a thousand million people do not have access to safe water, that is safe from coliform bacteria, cholera, typhoid fever, viral diarrhoeal disease, infectous hepatitis, poliomyelitis, parasites eg ascariasis, dracunculiasis , nematodes , trachoma and hookworm. 1.8 thousand million people do not have adequate sanitary facilities. Water shortage is a global health problem.

The diversion of rivers by damns upstream eg river Sajar in Syria has profound effects on the populations downstream. In some third world countries women spend 5 hours a day collecting water.

Websites

www.who.dk
specific environmental hazards UK

www.environment.detr.gov.uk
quality of water UK, Department of the Environment.