Plumbing is the system of pipes, drains, fittings, valves, and fixtures installed for the distribution of potable water for drinking, heating and washing, and waterborne waste removal. "Plumbing" also refers to the skilled trade which installs and maintains it. The plumbing industry is a basic and substantial part of every developed economy. The word derives from the Latin plumbum for lead, as the first effective pipes used in Roman era were lead pipes. "Plumbing" is often denotes the supply and waste system of an individual building, distinguishing it from water supply and sewage systems that serve a group of buildings.