Lead is a metal with no known biological benefit to humans. Too much lead can damage various systems of the body including the nervous and reproductive systems and the kidneys, and it can cause high blood pressure and anaemia. Lead accumulates in the bones and lead poisoning may be diagnosed from a blue line around the gums. Lead is especially harmful to the developing brains of foetuses and young children and to pregnant women. Lead interferes with the metabolism of calcium and vitamin D. High blood lead levels in children can cause consequences which may be irreversible including learning disabilities, behavioural problems, and mental retardation. At very high levels, lead can cause convulsions, coma and death. Lead can be dissolved in water when lead pipes are used for transportation of water. So, use of such pipes may be harmful to human being. hence lead-free plumbing system is most favoured for potable water transportation.