Water is the most common substance found on earth. It covers three-quarters of the earth's surface. Of all the earth's water, only one percent is available as a source of drinking water. Ninety-seven percent is salt water, located in oceans and seas, and two percent is frozen in the polar ice caps.
More than a third of the world's people lack a safe water supply. In underdeveloped areas, diarrhea causes 3.5 million deaths in children under age five every year. By 2025, more than two-thirds of the global population will live in countries with serious shortages of clean water.
Treated potable water travels through many kilometres of underground water mains from the treatment plant to the consumer's tap. Pipes that comprise the drinking water distribution system can include cast iron (CI) or asbestos-cement (AC) pipes, which are still in use today but are no longer installed. Cast ductile iron (DI) pipes and polyvinyl chloride (PVC) or vinyl pipes are also in use.
Water distribution pipes that corrode or break may cause contamination of the drinking water supply and subsequent outbreaks of waterborne diseases.
In the US, a study of the causes of waterborne disease outbreaks from 1971 to 1992 found that in community water systems, contamination of distribution systems was a significant factor.
Canadian municipalities have estimated annual water losses of $650 million, primarily through broken mains, plus expenditures of $82 million a year on repairs. This article has been abridged.