Original: Plumbing (from the Latin plumbum for lead, as pipes were once made from lead) is the skilled trade of working with pipes, tubing and plumbing fixtures for drinking water systems and the drainage of waste. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters.
Simplified: Plumbing also refers to a system of pipes and fixtures put in a building to move water and the get rid of waste that is in water.