Plumbing is the system of pipes, drains fittings, valves, valve assemblies, and devices installed in a building for the distribution of water for drinking, heating and washing, 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 and backflow preventers.Thus, plumbing usually deals with laying of pipe lines which provide a means of transportation for fluids. The plumbing industry is a basic and substantial part of every developed economy due to the need for clean water, and sanitary collection and transport of wastes. The word "plumbing" comes from the Latin plumbum for lead, as pipes were once made from lead.
Plumbing originated during ancient civilizations such as the Greek, Roman, Persian, Indian, and Chinese cities as they developed public baths and needed to provide potable water and drainage of wastes, for larger numbers of people. Standardized earthen 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. The Romans used lead pipe inscriptions to prevent water theft.
Improvement in plumbing systems was very slow, with virtually no progress made from the time of the Roman system of aqueducts and lead pipes. Plumbing was extremely rare until the growth of modern densely populated cities in the 1800s. During this period, public health authorities began pressing for better waste disposal systems to be installed, to prevent or control epidemics of disease. Earlier, the waste disposal system had merely consisted of collecting waste and dumping it on the ground or into a river. Eventually the development of separate, underground water and sewage systems eliminated open sewage ditches and cesspools.
Most large cities today pipe solid wastes to sewage treatment plants in order to separate and partially purify the water, before emptying into streams or other bodies of water. For potable water use, galvanized iron piping was commonplace in the United States from the late 1800s until around 1960. After that period, copper piping took over, first soft copper with flared fittings, then with rigid copper tubing utilizing soldered fittings.
The use of lead for potable water declined sharply after World War II because of increased awareness of the dangers of lead poisoning. At this time, copper piping was introduced as a better and safer alternative to lead pipes.
Water systems of ancient times relied on gravity for the supply of water, using pipes or channels usually made of clay, lead, bamboo, wood, or stone. Hollowed wooden logs wrapped in steel banding were used for plumbing pipes, particularly water mains. Logs were used for water distribution in England close to 500 years ago. US cities began using hollowed logs in the late 1700s through the 1800s.
Present-day water-supply systems use a network of high-pressure pumps, and pipes in buildings are now made of copper, brass, plastic (particularly cross-linked polyethylene called PEX, which is estimated to be used in 60% of single-family homes), or other nontoxic material. Due to its toxicity, lead has not been used in modern water-supply piping since the 1930s in the United States, although lead was used in plumbing solder for drinking water until it was banned in 1986. Drain and vent lines are made of plastic, steel, cast-iron, or lead.
The straight sections of plumbing systems are called "pipes" or "tubes". A pipe is typically formed via casting or welding, whereas a tube is made through extrusion. Pipe normally has thicker walls and may be threaded or welded, while tubing is thinner-walled and requires special joining techniques such as brazing, compression fitting, crimping, or for plastics, solvent welding. These joining techniques are discussed in more detail in the piping and plumbing fittings article.
In addition to lengths of pipe or tubing, pipe fittings are used in plumbing systems, such as valves, elbows, tees, and unions. Pipe and fittings are held in place with pipe hangers and strapping.
Plumbing fixtures are exchangeable devices using water that can be connected to a building's plumbing system. They are considered to be "fixtures", in that they are semi-permanent parts of buildings, not usually owned or maintained separately. Plumbing fixtures are seen by and designed for the end-users. Some 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.
Equipment and tools
Plumbing equipment includes devices often hidden behind walls or in utility spaces which are not seen by the general public. It includes water meters, pumps, expansion tanks, backflow arrestors, water filters, UV sterilization lights, water softeners, water heaters, heat exchangers, gauges, and control systems.
Specialized plumbing tools include pipe wrenches, flaring pliers,pipe vice,pipe bending machine,pipe cutter, dies and joining tools such as soldering torches and crimp tools. New tools have been developed to help plumbers fix problems more efficiently. For example, plumbers use video cameras for inspections of hidden leaks or problems, they use hydro jets, and high pressure hydraulic pumps connected to steel cables for trench-less sewer line replacement.
The major categories of plumbing systems or subsystems are:
- Potable cold and hot tap water supply
- Plumbing drainage venting
- Septic systems
- Rainwater, surface, and subsurface water drainage
- Fuel gas piping
For their environmental benefit and sizable energy savings, hot water heat recycling units are being installed in residential buildings. Ecological concerns and water shortages have increased interest in graywater recovery and treatment systems.
Plumbing may also include hydronics, which involves heating and cooling systems utilizing water to transport thermal energy. The New York City steam system is an example of a large district heating system.
Much of the plumbing work in populated areas is regulated by government or quasi-government agencies due to the direct impact on the public's 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 to future buyers. If permits are required for work, plumbing contractors typically secure them from the authorities on behalf of home or building owners.
In the United Kingdom the professional body is the 
In the United States, plumbing codes and licensing are generally controlled by state and local governments. At the national level, the Environmental Protection Agency has set guidelines about what constitutes lead-free plumbing fittings and pipes, in order to comply with the Safe Drinking Water Act.
Some widely used Standards in the United States are:
- ASME A112.6.3 – Floor and Trench Drains
- ASME A112.6.4 – Roof, Deck, and Balcony Drains
- ASME A112.18.1/CSA B125.1 – Plumbing Supply Fittings
- ASME A112.19.1/CSA B45.2 – Enameled Cast Iron and Enameled Steel Plumbing Fixtures
- ASME A112.19.2/CSA B45.1 – Ceramic Plumbing Fixtures
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- Uniform Plumbing Code, IAPMO
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- Media related to at Wikimedia Commons
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- Quotations related to Plumbing at Wikiquote
- at Wikibooks
- ATSDR Case Studies in Environmental Medicine: Lead Toxicity U.S. Department of Health and Human Services