The World Health Organization has announced what it calls a "paradigm shift" in efforts to safeguard global drinking water supplies. Newly published drinking water guidelines aim to prevent contamination before it occurs.

A recent WHO and UNICEF report says one billion people have no access to safe drinking water. The report says lack of clean water and sanitation kills nearly 4,000 children under five each day, and is also a major cause of death and disability for adults.

Water management guidelines have usually focused on responding to contamination problems. In shifting the focus to preventing contamination in a variety of drinking water systems, from piped and treated water supplies to wells and household treatment systems, the new guidelines offer advice on keeping water supplies free from animal and human waste, and set acceptable limits for chemical contaminants.

The aim is to help countries reach the U.N.'s Millennium Development Goal of reducing by half the number of people around the world without safe drinking water.