Plumbing is the system of pipes and drains installed in a building for the distribution of potable drinking water and the removal of waterborne wastes, and the skilled trade of working with pipes, tubing and plumbing fixtures in such systems. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters. The plumbing industry is a basic and substantial part of every developed economy due to the need for clean water, and proper collection and transport of wastes. The word "plumbing" comes from the Latin plumbum for lead, as pipes were once made from lead.

Plumbing is usually distinguished from water supply and sewage systems, in that a plumbing system serves one building, while water and sewage systems serve a group of buildings or a city.