Plumbing (from the Latin word plumbum, meaning "lead") is the skilled trade of working with pipes, tubing, and special fixtures for the distribution and use of water in a building and the drainage of waterborne waste. The term plumbing also refers to the pipes and fixtures that are part of such a system. Plumbing is usually distinguished from water and sewage systems, in that a plumbing system serves one building, whereas water and sewage systems serve a group of buildings or a city.
A plumber is a person 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.
Standardized earthenware plumbing pipes with broad flanges making use of asphalt for preventing leakages appeared in the urban settlements of the Indus Valley Civilization by 2700 B.C.E. Plumbing originated during the ancient civilizations, such as those of Greece, Rome, Persia, India, and China, as they developed public baths and needed to provide potable water and drainage of wastes. Improvement in plumbing systems was very slow, with virtually no progress made from the time of the Roman system of aqueducts and lead pipes until the nineteenth century. Eventually, the development of separate, underground water and sewage systems eliminated open sewage ditches and cesspools.
Plumbing equipment includes items such as water meters, pumps, expansion tanks, backflow preventers, filters, water softeners, water heaters, heat exchangers, gauges, and control systems.
In a plumbing system, water flows mainly through pipes and tubes. A pipe is typically formed via casting or welding, whereas a tube is made through extrusion. A pipe normally has thicker walls and may be threaded or welded, whereas tubing is thinner-walled and requires special joining techniques such as 'brazing', 'compression fitting', 'crimping', or (for plastics) 'solvent welding'.
In addition to pipes and tubing, plumbing systems require many fittings, such as valves, elbows, tees, and unions.
Plumbing fixtures are designed for end-users. Examples of fixtures include water closets (also known as toilets), urinals, bidets, showers, bathtubs, utility and kitchen sinks, drinking fountains, ice makers, humidifiers, air washers, fountains, and eye wash stations.
In ancient times, water systems relied on gravity for the supply of water, using pipes or channels usually made of clay, lead or stone. Present-day water-supply systems use a network of high-pressure pumps, and pipes are now made of copper, brass, plastic, steel, or other nontoxic material. Present-day drain and vent lines are made of plastic, steel, cast-iron, and lead. Lead is not used in modern water-supply piping due to its toxicity.
The major categories of plumbing systems or subsystems are:
For their environmental benefit and sizable energy savings hot water heat recycling units are growing in use throughout the residential building sectors. Further ecological concern has seen increasing interest in gray-water recovery and treatment systems.
Firestopping is required where mechanical penetrants traverse fire-resistance rated wall and floor assemblies, or membranes thereof. This work is usually done by workers in the insulation trade or specialty firestop sub-contractors.
Much of the plumbing work in populated areas (cities, towns, and so forth) is regulated by government or quasi-government agencies, due to the direct impact on public health, safety, and welfare. Plumbing installation and repair work on residences and other buildings generally must be done according to plumbing and building codes to protect the inhabitants of the buildings and to ensure safe, quality construction for future buyers. If permits are required for work, plumbing contractors typically secure them from the authorities on behalf of home or building owners.
In some parts of the world, however, the plumbing trade remains virtually ungoverned. There are few (if any) systems in place to monitor or control the activities of unqualified plumbers or those home owners who choose to undertake installation and maintenance works themselves, despite the health and safety issues that arise from such works when they are undertaken incorrectly.
The World Plumbing Council (WPC) has appointed a representative to the World Health Organization (WHO) to take forward various projects related to their joint publication, Health Aspects of Plumbing.
Plumbers can now take advantage of technologically advanced equipment that helps them fix problems without the usual hassles. For example, plumbers may use video cameras for inspections of hidden leaks or problems, and they may use hydro jets and high-pressure hydraulic pumps connected to steel cables for trench-less sewer line replacement.
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