Lead is a metal found in natural deposits. It is widely used in household pluming materials as well as water service lines.
Lead can be introduced into the drinking water through corrosion of your household pipes. In homes that were built before 1986 lead pipes were fairly common.
Negative health effects of consuming lead include delays in physical and mental development in babies and children, as well as deficits in attention span and learning capabilities.
In adults it has been linked to increased blood pressure as well as kidney problems.