Commercial Plumbing Services

Systems for conveying fluids

"Water pipe" redirects here. For the smoking device, see Bong and Hookah.

 

Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids.^[1] Heating and cooling (HVAC), waste removal, and potable water delivery are among the most common uses for plumbing, but it is not limited to these applications.^[2] The word derives from the Latin for lead, plumbum, as the first effective pipes used in the Roman era were lead pipes.^[3]

In the developed world, plumbing infrastructure is critical to public health and sanitation.^[4][5]

Boilermakers and pipefitters are not plumbers although they work with piping as part of their trade and their work can include some plumbing.

History

[edit]

Plumbing originated during ancient civilizations, as they developed public baths and needed to provide potable water and wastewater removal for larger numbers of people.^[6]

The Mesopotamians introduced the world to clay sewer pipes around 4000 BCE, with the earliest examples found in the Temple of Bel at Nippur and at Eshnunna,^[7] used to remove wastewater from sites, and capture rainwater, in wells. The city of Uruk contains the oldest known examples of brick constructed Latrines, constructed atop interconnecting fired clay sewer pipes, c. 3200 BCE.^[8][9] Clay pipes were later used in the Hittite city of Hattusa.^[10] They had easily detachable and replaceable segments, and allowed for cleaning.

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 BC.^[11]

Copper piping appeared in Egypt by 2400 BCE, with the Pyramid of Sahure and adjoining temple complex at Abusir, found to be connected by a copper waste pipe.^[12]

The word "plumber" dates from the Roman Empire.^[13] The Latin for lead is plumbum. Roman roofs used lead in conduits and drain pipes^[14] and some were also covered with lead. Lead was also used for piping and for making baths.^[15]

Plumbing reached its early apex in ancient Rome, which saw the introduction of expansive systems of aqueducts, tile wastewater removal, and widespread use of lead pipes. The Romans used lead pipe inscriptions to prevent water theft. With the Fall of Rome both water supply and sanitation stagnated—or regressed—for well over 1,000 years. Improvement was very slow, with little effective progress made 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 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.

In post-classical Kilwa the wealthy enjoyed indoor plumbing in their stone homes.^[16][17]

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 using 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.^[18]

The major categories of plumbing systems or subsystems are:^[19]

• potable cold and hot tap water supply
• plumbing drainage venting
• sewage systems and septic systems with or without hot water heat recycling and graywater recovery and treatment systems
• Rainwater, surface, and subsurface water drainage
• fuel gas piping
• hydronics, i.e. heating and cooling systems using water to transport thermal energy, as in district heating systems, like for example the New York City steam system.

A water pipe is a pipe or tube, frequently made of plastic or metal,^[a] that carries pressurized and treated fresh water to a building (as part of a municipal water system), as well as inside the building.

Lead was the favoured material for water pipes for many centuries because its malleability made it practical to work into the desired shape. Such use was so common that the word "plumbing" derives from plumbum, the Latin word for lead. This was a source of lead-related health problems in the years before the health hazards of ingesting lead were fully understood; among these were stillbirths and high rates of infant mortality. Lead water pipes were still widely used in the early 20th century and remain in many households. Lead-tin alloy solder was commonly used to join copper pipes, but modern practice uses tin-antimony alloy solder instead in order to eliminate lead hazards.^[20]

Despite the Romans' common use of lead pipes, their aqueducts rarely poisoned people. Unlike other parts of the world where lead pipes cause poisoning, the Roman water had so much calcium in it that a layer of plaque prevented the water contacting the lead itself. What often causes confusion is the large amount of evidence of widespread lead poisoning, particularly amongst those who would have had easy access to piped water,^[21] an unfortunate result of lead being used in cookware and as an additive to processed food and drink (for example as a preservative in wine).^[22] Roman lead pipe inscriptions provided information on the owner to prevent water theft.

Wooden pipes were used in London and elsewhere during the 16th and 17th centuries. The pipes were hollowed-out logs which were tapered at the end with a small hole in which the water would pass through.^[23] The multiple pipes were then sealed together with hot animal fat. Wooden pipes were used in Philadelphia,^[24] Boston, and Montreal in the 1800s. Built-up wooden tubes were widely used in the US during the 20th century. These pipes (used in place of corrugated iron or reinforced concrete pipes) were made of sections cut from short lengths of wood. Locking of adjacent rings with hardwood dowel pins produced a flexible structure. About 100,000 feet of these wooden pipes were installed during WW2 in drainage culverts, storm sewers and conduits, under highways and at army camps, naval stations, airfields and ordnance plants.

Cast iron and ductile iron pipe was long a lower-cost alternative to copper before the advent of durable plastic materials but special non-conductive fittings must be used where transitions are to be made to other metallic pipes (except for terminal fittings) in order to avoid corrosion owing to electrochemical reactions between dissimilar metals (see galvanic cell).^[25]

Bronze fittings and short pipe segments are commonly used in combination with various materials.^[26]

The difference between pipes and tubes is a matter of sizing. For instance, PVC pipe for plumbing applications and galvanized steel pipe are measured in iron pipe size (IPS). Copper tube, CPVC, PeX and other tubing is measured nominally, basically an average diameter. These sizing schemes allow for universal adaptation of transitional fittings. For instance, 1/2" PeX tubing is the same size as 1/2" copper tubing. 1/2" PVC on the other hand is not the same size as 1/2" tubing, and therefore requires either a threaded male or female adapter to connect them. When used in agricultural irrigation, the singular form "pipe" is often used as a plural.^[27]

Pipe is available in rigid joints, which come in various lengths depending on the material. Tubing, in particular copper, comes in rigid hard tempered joints or soft tempered (annealed) rolls. PeX and CPVC tubing also comes in rigid joints or flexible rolls. The temper of the copper, whether it is a rigid joint or flexible roll, does not affect the sizing.^[27]

The thicknesses of the water pipe and tube walls can vary. Because piping and tubing are commodities, having a greater wall thickness implies higher initial cost. Thicker walled pipe generally implies greater durability and higher pressure tolerances. Pipe wall thickness is denoted by various schedules or for large bore polyethylene pipe in the UK by the Standard Dimension Ratio (SDR), defined as the ratio of the pipe diameter to its wall thickness. Pipe wall thickness increases with schedule, and is available in schedules 20, 40, 80, and higher in special cases. The schedule is largely determined by the operating pressure of the system, with higher pressures commanding greater thickness. Copper tubing is available in four wall thicknesses: type DWV (thinnest wall; only allowed as drain pipe per UPC), type 'M' (thin; typically only allowed as drain pipe by IPC code), type 'L' (thicker, standard duty for water lines and water service), and type 'K' (thickest, typically used underground between the main and the meter).

Wall thickness does not affect pipe or tubing size.^[28] 1/2" L copper has the same outer diameter as 1/2" K or M copper. The same applies to pipe schedules. As a result, a slight increase in pressure losses is realized due to a decrease in flowpath as wall thickness is increased. In other words, 1 foot of 1/2" L copper has slightly less volume than 1 foot of 1/2 M copper.^[29]

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. Today, most plumbing supply pipe is made out of steel, copper, and plastic; most waste (also known as "soil")^[30] out of steel, copper, plastic, and cast iron.^[30]

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.

Galvanized steel potable water supply and distribution pipes are commonly found with nominal pipe sizes from 3⁄8 inch (9.5 mm) to 2 inches (51 mm). It is rarely used today for new construction residential plumbing. Steel pipe has National Pipe Thread (NPT) standard tapered male threads, which connect with female tapered threads on elbows, tees, couplers, valves, and other fittings. Galvanized steel (often known simply as "galv" or "iron" in the plumbing trade) is relatively expensive, and difficult to work with due to weight and requirement of a pipe threader. It remains in common use for repair of existing "galv" systems and to satisfy building code non-combustibility requirements typically found in hotels, apartment buildings and other commercial applications. It is also extremely durable and resistant to mechanical abuse. Black lacquered steel pipe is the most widely used pipe material for fire sprinklers and natural gas.

Most typical single family home systems will not require supply piping larger than

3⁄4 inch (19 mm) due to expense as well as steel piping's tendency to become obstructed from internal rusting and mineral deposits forming on the inside of the pipe over time once the internal galvanizing zinc coating has degraded. In potable water distribution service, galvanized steel pipe has a service life of about 30 to 50 years, although it is not uncommon for it to be less in geographic areas with corrosive water contaminants.

Copper pipe and tubing was widely used for domestic water systems in the latter half of the twentieth century. Demand for copper products has fallen due to the dramatic increase in the price of copper, resulting in increased demand for alternative products including PEX and stainless steel.

Plastic pipe is in wide use for domestic water supply and drain-waste-vent (DWV) pipe. Principal types include: Polyvinyl chloride (PVC) was produced experimentally in the 19th century but did not become practical to manufacture until 1926, when Waldo Semon of BF Goodrich Co. developed a method to plasticize PVC, making it easier to process. PVC pipe began to be manufactured in the 1940s and was in wide use for Drain-Waste-Vent piping during the reconstruction of Germany and Japan following WWII. In the 1950s, plastics manufacturers in Western Europe and Japan began producing acrylonitrile butadiene styrene (ABS) pipe. The method for producing cross-linked polyethylene (PEX) was also developed in the 1950s. Plastic supply pipes have become increasingly common, with a variety of materials and fittings employed.

• PVC/CPVC – rigid plastic pipes similar to PVC drain pipes but with thicker walls to deal with municipal water pressure, introduced around 1970. PVC stands for polyvinyl chloride, and it has become a common replacement for metal piping. PVC should be used only for cold water, or for venting. CPVC can be used for hot and cold potable water supply. Connections are made with primers and solvent cements as required by code.^[31]
• PP – The material is used primarily in housewares, food packaging, and clinical equipment,^[32] but since the early 1970s has seen increasing use worldwide for both domestic hot and cold water. PP pipes are heat fused, being unsuitable for the use of glues, solvents, or mechanical fittings. PP pipe is often used in green building projects.^[33]
• PBT – flexible (usually gray or black) plastic pipe which is attached to barbed fittings and secured in place with a copper crimp ring. The primary manufacturer of PBT tubing and fittings was driven into bankruptcy by a class-action lawsuit over failures of this system.^{[citation needed]} However, PB and PBT tubing has since returned to the market and codes, typically first for "exposed locations" such as risers.
• PEX – cross-linked polyethylene system with mechanically joined fittings employing barbs, and crimped steel or copper rings.
• Polytanks – plastic polyethylene cisterns, underground water tanks, above ground water tanks, are usually made of linear polyethylene suitable as a potable water storage tank, provided in white, black or green.
• Aqua – known as PEX-Al-PEX, for its PEX/aluminum sandwich, consisting of aluminum pipe sandwiched between layers of PEX, and connected with modified brass compression fittings. In 2005, many of these fittings were recalled.^{[further explanation needed]}

Present-day water-supply systems use a network of high-pressure pumps, and pipes in buildings are now made of copper,^[34] brass, plastic (particularly cross-linked polyethylene called PEX, which is estimated to be used in 60% of single-family homes^[35]), or other nontoxic material. Due to its toxicity, most cities moved away from lead water-supply piping by the 1920s in the United States,^[36] although lead pipes were approved by national plumbing codes into the 1980s,^[37] and lead was used in plumbing solder for drinking water until it was banned in 1986.^[36] Drain and vent lines are made of plastic, steel, cast iron, or lead.^[38][39]

• 
  Monument to water pipe in Mytishchi (Russia)
• 
  A specific water pipe made for use with pressure vessels. The pipe can sustain high-pressure water and is relatively small.
• 
  Concrete water pipe
• 
  Connecting to an existing water line (white pipe) with a stainless steel tapping sleeve and valve (red). A concrete thrust block is being formed behind the new connection.
• 
  Water pipe connected to the septic tank.
• 
  Sewer pipe

In addition to lengths of pipe or tubing, pipe fittings such as valves, elbows, tees, and unions. are used in plumbing systems.^[40] Pipe and fittings are held in place with pipe hangers and strapping.

Plumbing fixtures are exchangeable devices that use water and 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^[41] (also known as toilets), urinals, bidets, showers, bathtubs, utility and kitchen sinks, drinking fountains, ice makers, humidifiers, air washers, fountains, and eye wash stations.

Threaded pipe joints are sealed with thread seal tape or pipe dope. Many plumbing fixtures are sealed to their mounting surfaces with plumber's putty.^[42]

Plumbing equipment includes devices often behind walls or in utility spaces which are not seen by the general public. It includes water meters, pumps, expansion tanks, back flow preventers, water filters, UV sterilization lights, water softeners, water heaters, heat exchangers, gauges, and control systems.

There are many tools a plumber needs to do a good plumbing job. While many simple plumbing tasks can be completed with a few common hand held tools, other more complex jobs require specialised tools, designed specifically to make the job easier.

Specialized plumbing tools include pipe wrenches, flaring pliers, pipe vise, 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 other problems; they also use hydro jets, and high pressure hydraulic pumps connected to steel cables for trench-less sewer line replacement.

Flooding from excessive rain or clogged sewers may require specialized equipment, such as a heavy duty pumper truck designed to vacuum raw sewage.^{[citation needed]}

Bacteria have been shown to live in "premises plumbing systems". The latter refers to the "pipes and fixtures within a building that transport water to taps after it is delivered by the utility".^[43] Community water systems have been known for centuries to spread waterborne diseases like typhoid and cholera. However, "opportunistic premises plumbing pathogens" have been recognized only more recently: Legionella pneumophila, discovered in 1976, Mycobacterium avium, and Pseudomonas aeruginosa are the most commonly tracked bacteria, which people with depressed immunity can inhale or ingest and may become infected with.^[44] Some of the locations where these opportunistic pathogens can grow include faucets, shower heads, water heaters and along pipe walls. Reasons that favor their growth are "high surface-to-volume ratio, intermittent stagnation, low disinfectant residual, and warming cycles". A high surface-to-volume ratio, i.e. a relatively large surface area allows the bacteria to form a biofilm, which protects them from disinfection.^[44]

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.^{[citation needed]}

In Australia, the national governing body for plumbing regulation is the Australian Building Codes Board. They are responsible for the creation of the National Construction Code (NCC), Volume 3 of which, the Plumbing Regulations 2008^[45] and the Plumbing Code of Australia,^[46] pertains to plumbing.

Each Government at the state level has their own Authority and regulations in place for licensing plumbers. They are also responsible for the interpretation, administration and enforcement of the regulations outlined in the NCC.^[47] These Authorities are usually established for the sole purpose of regulating plumbing activities in their respective states/territories. However, several state level regulation acts are quite outdated, with some still operating on local policies introduced more than a decade ago. This has led to an increase in plumbing regulatory issues not covered under current policy, and as such, many policies are currently being updated to cover these more modern issues. The updates include changed to the minimum experience and training requirements for licensing, additional work standards for new and more specific kinds of plumbing, as well as adopting the Plumbing Code of Australia into state regulations in an effort to standardise plumbing regulations across the country.

In Norway, new domestic plumbing installed since 1997 has had to satisfy the requirement that it should be easily accessible for replacement after installation.^[48] This has led to the development of the pipe-in-pipe system as a de facto requirement for domestic plumbing.

In the United Kingdom the professional body is the Chartered Institute of Plumbing and Heating Engineering (educational charity status) and it is true that the trade still remains virtually ungoverned;^[49] there are no 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 which arise from such works when they are undertaken incorrectly; see Health Aspects of Plumbing (HAP) published jointly by the World Health Organization (WHO) and the World Plumbing Council (WPC).^[50][51] WPC has subsequently appointed a representative to the World Health Organization to take forward various projects related to Health Aspects of Plumbing.^[52]

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.^[53]

Some widely used Standards in the United States are:^{[citation needed]}

• 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

In Canada, plumbing is a regulated trade requiring specific technical training and certification. Standards and regulations for plumbing are overseen at the provincial and territorial level, each having its distinct governing body:

• Governing Bodies: Each province or territory possesses its regulatory authority overseeing the licensing and regulation of plumbers. For instance, in Ontario, the Ontario College of Trades handles the certification and regulation of tradespeople, whereas in British Columbia, the Industry Training Authority (ITA) undertakes this function.

• Certification: To achieve certified plumber status in Canada, individuals typically complete an apprenticeship program encompassing both classroom instruction and hands-on experience. Upon completion, candidates undergo an examination for their certification.

• Building Codes: Plumbing installations and repairs must adhere to building codes specified by individual provinces or territories. The National Building Code of Canada acts as a model code, with provinces and territories having the discretion to adopt or modify to their specific needs.

• Safety and Health: Given its direct correlation with health and sanitation, plumbing work is of paramount importance in Canada. Regulations ensure uncontaminated drinking water and proper wastewater treatment, underscoring the vital role of certified plumbers for public health.

• Environmental Considerations: Reflecting Canada's commitment to environmental conservation, there is an increasing emphasis on sustainable plumbing practices. Regulations advocate water conservation and the deployment of eco-friendly materials.

• Standards: The Canadian Standards Association (CSA) determines standards for diverse plumbing products, ensuring their safety, quality, and efficiency. Items such as faucets and toilets frequently come with a CSA certification, indicating adherence to required standards.^[54]

• Teresi, Dick (2002). Lost Discoveries: The Ancient Roots of Modern Science--from the Babylonians to the Maya. New York: Simon & Schuster. pp. 351–352. ISBN 0-684-83718-8.

Wikimedia Commons has media related to Plumbing.

Look up plumbing in Wiktionary, the free dictionary.

Wikiquote has quotations related to Plumbing.

Wikibooks has more on the topic of: Plumbing

• Lead Water Pipes and Infant Mortality in Turn-of-the-Century Massachusetts

Agency for Toxic Substances and Disease Registry:

• ATSDR Case Studies in Environmental Medicine: Lead Toxicity
• Case Studies in Environmental Medicine—Lead Toxicity
• ToxFAQs: Lead

Part of a series on
Pollution
Air pollution from a factory
Air Acid rain Air quality index Atmospheric dispersion modeling Chlorofluorocarbon Combustion Exhaust gas Haze Household air pollution Global dimming Global distillation Indoor air quality Non-exhaust emissions Ozone depletion Particulates Persistent organic pollutant Smog Soot Volatile organic compound
Biological Biological hazard Genetic Illegal logging Introduced species Invasive species
Digital Information
Electromagnetic Light Ecological Overillumination Radio spectrum
Natural Ozone Radium and radon in the environment Volcanic ash Wildfire
Noise Transportation Health effects from noise Marine mammals and sonar Noise barrier Noise control Soundproofing
Radiation Actinides Bioremediation Depleted uranium Nuclear fission Nuclear fallout Plutonium Poisoning Radioactivity Uranium Radioactive waste
Soil Agricultural Land degradation Bioremediation Defecation Electrical resistance heating Illegal mining Soil guideline values Phytoremediation
Solid waste Advertising mail Biodegradable waste Brown waste Electronic waste Food waste Green waste Hazardous waste Industrial waste Litter Mining Municipal solid waste Nanomaterials Plastic Packaging waste Post-consumer waste Waste management
Space Space debris
Visual Air travel Advertising clutter Overhead power lines Traffic signs Urban blight Vandalism
War Chemical warfare Herbicidal warfare Agent Orange Nuclear holocaust Nuclear fallout Nuclear famine Nuclear winter Scorched earth Unexploded ordnance War and environmental law
Water Agricultural wastewater Biosolids Diseases Eutrophication Firewater Freshwater Groundwater Hypoxia Industrial wastewater Marine Monitoring Nonpoint source Nutrient Ocean acidification Oil spill Pharmaceuticals Freshwater salinization Septic tanks Sewage Shipping Sludge Stagnation Sulfur water Surface runoff Turbidity Urban runoff Water quality Wastewater
Topics History Pollutants Heavy metals Paint
Misc Area source Brain health and pollution Debris Dust Garbology Legacy Thermal pollution Midden Point source Waste Toxic Lists Diseases Law by country Most polluted cities Least polluted cities by PM2.5 Treaties Most polluted rivers Categories By country
Environment portal Ecology portal

Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system.^{[1]: 175â€ÅÂÂ}  Sewage consists of wastewater discharged from residences and from commercial, institutional and public facilities that exist in the locality.^{[2]: 10â€ÅÂÂ}  Sub-types of sewage are greywater (from sinks, bathtubs, showers, dishwashers, and clothes washers) and blackwater (the water used to flush toilets, combined with the human waste that it flushes away). Sewage also contains soaps and detergents. Food waste may be present from dishwashing, and food quantities may be increased where garbage disposal units are used. In regions where toilet paper is used rather than bidets, that paper is also added to the sewage. Sewage contains macro-pollutants and micro-pollutants, and may also incorporate some municipal solid waste and pollutants from industrial wastewater.

Sewage usually travels from a building's plumbing either into a sewer, which will carry it elsewhere, or into an onsite sewage facility. Collection of sewage from several households together usually takes places in either sanitary sewers or combined sewers. The former is designed to exclude stormwater flows whereas the latter is designed to also take stormwater. The production of sewage generally corresponds to the water consumption. A range of factors influence water consumption and hence the sewage flowrates per person. These include: Water availability (the opposite of water scarcity), water supply options, climate (warmer climates may lead to greater water consumption), community size, economic level of the community, level of industrialization, metering of household consumption, water cost and water pressure.^{[2]: 20â€ÅÂÂ} 

The main parameters in sewage that are measured to assess the sewage strength or quality as well as treatment options include: solids, indicators of organic matter, nitrogen, phosphorus, and indicators of fecal contamination.^{[2]: 33â€ÅÂÂ}  These can be considered to be the main macro-pollutants in sewage. Sewage contains pathogens which stem from fecal matter. The following four types of pathogens are found in sewage: pathogenic bacteria, viruses, protozoa (in the form of cysts or oocysts) and helminths (in the form of eggs).^[3][4] In order to quantify the organic matter, indirect methods are commonly used: mainly the Biochemical Oxygen Demand (BOD) and the Chemical Oxygen Demand (COD).^{[2]: 36â€ÅÂÂ} 

Management of sewage includes collection and transport for release into the environment, after a treatment level that is compatible with the local requirements for discharge into water bodies, onto soil or for reuse applications.^{[2]: 156â€ÅÂÂ}  Disposal options include dilution (self-purification of water bodies, making use of their assimilative capacity if possible), marine outfalls, land disposal and sewage farms. All disposal options may run risks of causing water pollution.

Sewage (or domestic wastewater) consists of wastewater discharged from residences and from commercial, institutional and public facilities that exist in the locality.^{[2]: 10â€ÅÂÂ}  Sewage is a mixture of water (from the community's water supply), human excreta (feces and urine), used water from bathrooms, food preparation wastes, laundry wastewater, and other waste products of normal living.

Sewage from municipalities contains wastewater from commercial activities and institutions, e.g. wastewater discharged from restaurants, laundries, hospitals, schools, prisons, offices, stores and establishments serving the local area of larger communities.^{[2]: 21â€ÅÂÂ} 

Sewage can be distinguished into "untreated sewage" (also called "raw sewage") and "treated sewage" (also called "effluent" from a sewage treatment plant).

The term "sewage" is nowadays often used interchangeably with "wastewater" – implying "municipal wastewater" – in many textbooks, policy documents and the literature.^[2][5][6] To be precise, wastewater is a broader term, because it refers to any water after it has been used in a variety of applications.^{[5]: 1â€ÅÂÂ}  Thus it may also refer to "industrial wastewater", agricultural wastewater and other flows that are not related to household activities.

The overall appearance of sewage is as follows:^{[2]: 30â€ÅÂÂ}  The temperature tends to be slightly higher than in drinking water but is more stable than the ambient temperature. The color of fresh sewage is slightly grey, whereas older sewage (also called "septic sewage") is dark grey or black. The odor of fresh sewage is "oily" and relatively unpleasant, whereas older sewage has an unpleasant foul odor due to hydrogen sulfide gas and other decomposition by-products.^{[10]: 9–38â€ÅÂÂ}  Sewage can have high turbidity from suspended solids.

The pH value of sewage is usually near neutral, and can be in the range of 6.7–8.0.^{[2]: 57â€ÅÂÂ} 

Sewage consists primarily of water and usually contains less than one part of solid matter per thousand parts of water. In other words, one can say that sewage is composed of around 99.9% pure water, and the remaining 0.1% are solids, which can be in the form of either dissolved solids or suspended solids.^{[2]: 28â€ÅÂÂ}  The thousand-to-one ratio is an order of magnitude estimate rather than an exact percentage because, aside from variation caused by dilution, solids may be defined differently depending upon the mechanism used to separate those solids from the liquid fraction. Sludges of settleable solids removed by settling or suspended solids removed by filtration may contain significant amounts of entrained water, while dried solid material remaining after evaporation eliminates most of that water but includes dissolved minerals not captured by filtration or gravitational separation.^[11] The suspended and dissolved solids include organic and inorganic matter plus microorganisms.^{[2]: 28â€ÅÂÂ} 

About one-third of this solid matter is suspended by turbulence, while the remainder is dissolved or colloidal. For the situation in the United States in the 1950s it was estimated that the waste contained in domestic sewage is about half organic and half inorganic.^{[10]: 9–38â€ÅÂÂ} 

The organic matter in sewage can be classified in terms of form and size: Suspended (particulate) or dissolved (soluble). Secondly, it can be classified in terms of biodegradability: either inert or biodegradable.^{[2]: 35â€ÅÂÂ}  The organic matter in sewage consists of protein compounds (about 40%), carbohydrates (about 25–50%), oils and grease (about 10%) and urea, surfactants, phenols, pesticides and others (lower quantity).^{[2]: 35â€ÅÂÂ}  In order to quantify the organic matter content, it is common to use "indirect methods" which are based on the consumption of oxygen to oxidize the organic matter: mainly the Biochemical Oxygen Demand (BOD) and the Chemical Oxygen Demand (COD).^{[2]: 36â€ÅÂÂ}  These indirect methods are associated with the major impact of the discharge of organic matter into water bodies: the organic matter will be food for microorganisms, whose population will grow, and lead to the consumption of oxygen, which may then affect aquatic living organisms.

The mass load of organic content is calculated as the sewage flowrate multiplied with the concentration of the organic matter in the sewage.^{[2]: 55â€ÅÂÂ} 

Typical values for physical–chemical characteristics of raw sewage is provided further down below.

Apart from organic matter, sewage also contains nutrients. The major nutrients of interest are nitrogen and phosphorus. If sewage is discharged untreated, its nitrogen and phosphorus content can lead to pollution of lakes and reservoirs via a process called eutrophication.^{[2]: 77â€ÅÂÂ} 

In raw sewage, nitrogen exists in the two forms of organic nitrogen or ammonia. The ammonia stems from the urea in urine. Urea is rapidly hydrolyzed and therefore not usually found in raw sewage.^{[2]: 43â€ÅÂÂ} 

Total phosphorus is mostly present in sewage in the form of phosphates.They are either inorganic (polyphosphates and orthophosphates) and their main source is from detergents and other household chemical products. The other form is organic phosphorus, where the source is organic compounds to which the organic phosphorus is bound.^{[2]: 45â€ÅÂÂ} 

Human feces in sewage may contain pathogens capable of transmitting diseases.^{[10]: 9–38â€ÅÂÂ}  The following four types of pathogens are found in sewage:^[3][4]

• Bacteria like Salmonella, Shigella, Campylobacter, or Vibrio cholerae;
• Viruses like hepatitis A, rotavirus, coronavirus,^[12] enteroviruses;
• Protozoa like Entamoeba histolytica, Giardia lamblia, Cryptosporidium parvum; and
• Helminths and their eggs including Ascaris (roundworm), Ancylostoma (hookworm), and Trichuris (whipworm)

In most practical cases, pathogenic organisms are not directly investigated in laboratory analyses. An easier way to assess the presence of fecal contamination is by assessing the most probable numbers of fecal coliforms (called thermotolerant coliforms), especially Escherichia coli. Escherichia coli are intestinal bacteria excreted by all warm blooded animals, including human beings, and thus tracking their presence in sewage is easy, because of their substantially high concentrations (around 10 to 100 million per 100 mL).^{[2]: 52â€ÅÂÂ} 

The ability of a flush toilet to make things "disappear" is soon recognized by young children who may experiment with virtually anything they can carry to the toilet.^[13] Adults may be tempted to dispose of toilet paper, wet wipes, diapers, sanitary napkins, tampons, tampon applicators, condoms, and expired medications, even at the risk of causing blockages. The privacy of a toilet offers a clandestine means of removing embarrassing evidence by flushing such things as drug paraphernalia, pregnancy test kits, combined oral contraceptive pill dispensers, and the packaging for those devices. There may be reluctance to retrieve items like children's toys or toothbrushes which accidentally fall into toilets, and items of clothing may be found in sewage from prisons or other locations where occupants may be careless.^[14] Trash and garbage in streets may be carried to combined sewers by stormwater runoff.

Sewage contains environmental persistent pharmaceutical pollutants. Trihalomethanes can also be present as a result of past disinfection. Sewage may contain microplastics such as polyethylene and polypropylene beads, or polyester and polyamide fragments^[15] from synthetic clothing and bedding fabrics abraded by wear and laundering, or from plastic packaging and plastic-coated paper products disintegrated by lift station pumps. Pharmaceuticals, endocrine disrupting compounds, and hormones^[16][17][18] may be excreted in urine or feces if not catabolized within the human body.

Some residential users tend to pour unwanted liquids like used cooking oil,^{[19]: 228â€ÅÂÂ}  lubricants,^{[19]: 228â€ÅÂÂ}  adhesives, paint, solvents, detergents,^{[19]: 228â€ÅÂÂ}  and disinfectants into their sewer connections. This behavior can result in problems for the treatment plant operation and is thus discouraged.

The composition of sewage varies with climate, social and economic situation and population habits.^{[2]: 28â€ÅÂÂ}  In regions where water use is low, the strength of the sewage (or pollutant concentrations) is much higher than that in the United States where water use per person is high.^{[5]: 183â€ÅÂÂ}  Household income and diet also plays a role: For example, for the case of Brazil, it has been found that the higher the household income, the higher is the BOD load per person and the lower is the BOD concentration.^{[2]: 57â€ÅÂÂ} 

Typical values for physical–chemical characteristics of raw sewage in developing countries have been published as follows: 180 g/person/d for total solids (or 1100 mg/L when expressed as a concentration), 50 g/person/d for BOD (300 mg/L), 100 g/person/d for COD (600 mg/L), 8 g/person/d for total nitrogen (45 mg/L), 4.5 g/person/d for ammonia-N (25 mg/L) and 1.0 g/person/d for total phosphorus (7 mg/L).^{[2]: 57â€ÅÂÂ}  The typical ranges for these values are: 120–220 g/person/d for total solids (or 700–1350 mg/L when expressed as a concentration), 40–60 g/person/d for BOD (250–400 mg/L), 80–120 g/person/d for COD (450–800 mg/L), 6–10 g/person/d for total nitrogen (35–60 mg/L), 3.5–6 g/person/d for ammonia-N (20–35 mg/L) and 0.7–2.5 g/person/d for total phosphorus (4–15 mg/L).^{[2]: 57â€ÅÂÂ} 

For high income countries, the "per person organic matter load" has been found to be approximately 60 gram of BOD per person per day.^[6] This is called the population equivalent (PE) and is also used as a comparison parameter to express the strength of industrial wastewater compared to sewage.

Values for households in the United States have been published as follows, whereby the estimates are based on the assumption that 25% of the homes have kitchen waste-food grinders (sewage from such households contain more waste): 95 g/person/d for total suspended solids (503 mg/L concentration), 85 g/person/d for BOD (450 mg/L), 198 g/person/d for COD (1050 mg/L), 13.3 g/person/d for the sum of organic nitrogen and ammonia nitrogen (70.4 mg/L), 7.8 g/person/d for ammonia-N (41.2 mg/L) and 3.28 g/person/d for total phosphorus (17.3 mg/L). The concentration values given here are based on a flowrate of 190 L per person per day.^{[5]: 183â€ÅÂÂ} 

A United States source published in 1972 estimated that the daily dry weight of solid wastes per capita in sewage is estimated as 20.5 g (0.72 oz) in feces, 43.3 g (1.53 oz) of dissolved solids in urine, 20 g (0.71 oz) of toilet paper, 86.5 g (3.05 oz) of greywater solids, 30 g (1.1 oz) of food solids (if garbage disposal units are used), and varying amounts of dissolved minerals depending upon salinity of local water supplies, volume of water use per capita, and extent of water softener use.^{[19]: 234â€ÅÂÂ} 

Sewage contains urine and feces. The mass of feces varies with dietary fiber intake. An average person produces 128 grams of wet feces per day, or a median dry mass of 29 g/person/day.^[20] The median urine generation rate is about 1.42 L/person/day, as was determined by a global literature review.^[20]

The volume of domestic sewage produced per person (or "per capita", abbreviated as "cap") varies with the water consumption in the respective locality.^{[2]: 11â€ÅÂÂ}  A range of factors influence water consumption and hence the sewage flowrates per person. These include: Water availability (the opposite of water scarcity), water supply options, climate (warmer climates may lead to greater water consumption), community size, economic level of the community, level of industrialization, metering of household consumption, water cost and water pressure.^{[2]: 20â€ÅÂÂ} 

The production of sewage generally corresponds to the water consumption. However water used for landscape irrigation will not enter the sewer system, while groundwater and stormwater may enter the sewer system in addition to sewage.^{[2]: 22â€ÅÂÂ}  There are usually two peak flowrates of sewage arriving at a treatment plant per day: One peak is at the beginning of the morning and another peak is at the beginning of the evening.^{[2]: 24â€ÅÂÂ} 

With regards to water consumption, a design figure that can be regarded as "world average" is 35–90 L per person per day (data from 1992).^{[5]: 163â€ÅÂÂ}  The same publication listed the water consumption in China as 80 L per person per day, Africa as 15–35 L per person per day, Eastern Mediterranean in Europe as 40–85 L per person per day and Latin America and Caribbean as 70–190 L per person per day.^{[5]: 163â€ÅÂÂ}  Even inside a country, there may be large variations from one region to another due to the various factors that determine the water consumption as listed above.

A flowrate value of 200 liters of sewage per person per day is often used as an estimate in high income countries, and is used for example in the design of sewage treatment plants.^[6]

For comparison, typical sewage flowrates from urban residential sources in the United States are estimated as follows: 365 L/person/day (for one person households), 288 L/person/day (two person households), 200 L/person/day (four person households), 189 L/person/day (six person households).^{[5]: 156â€ÅÂÂ}  This means the overall range for this example would be 189–365 L (42–80 imp gal; 50–96 US gal).

Sewage can be monitored for both disease-causing and benign organisms with a variety of techniques. Traditional techniques involve filtering, staining, and examining samples under a microscope. Much more sensitive and specific testing can be accomplished with DNA sequencing, such as when looking for rare organisms, attempting eradication, testing specifically for drug-resistant strains, or discovering new species.^[22][23][24] Sequencing DNA from an environmental sample is known as metagenomics.

Sewage has also been analyzed to determine relative rates of use of prescription and illegal drugs among municipal populations.^[25] General socioeconomic demographics may be inferred as well.^[26]

Sewage is commonly collected and transported in gravity sewers, either in a sanitary sewer or in a combined sewer. The latter also conveys urban runoff (stormwater) which means the sewage gets diluted during rain events.^{[2]: 9â€ÅÂÂ} 

Infiltration is groundwater entering sewer pipes through defective pipes, connections, joints or manholes.^{[2]: 26 [5]: 164â€ÅÂÂ}  Contaminated or saline groundwater may introduce additional pollutants to the sewage. The amount of such infiltrated water depends on several parameters, such as the length of the collection network, pipeline diameters, drainage area, soil type, water table depth, topography and number of connections per unit area.^{[2]: 26â€ÅÂÂ}  Infiltration is increased by poor construction procedures, and tends to increase with the age of the sewer. The amount of infiltration varies with the depth of the sewer in comparison to the local groundwater table.^{[10]: 9–1, 9–9â€ÅÂÂ}  Older sewer systems that are in need of rehabilitation may also exfiltrate sewage into groundwater from the leaking sewer joints and service connections.^{[5]: 167â€ÅÂÂ}  This can lead to groundwater pollution.^[28]

Combined sewers are designed to transport sewage and stormwater together. This means that sewage becomes diluted during rain events. There are other types of inflow that also dilute sewage, e.g. "water discharged from cellar and foundation drains, cooling-water discharges, and any direct stormwater runoff connections to the sanitary collection system".^{[5]: 163â€ÅÂÂ}  The "direct inflows" can result in peak sewage flowrates similar to combined sewers during wet weather events.^{[5]: 165â€ÅÂÂ} 

Sewage from communities with industrial facilities may include some industrial wastewater, generated by industrial processes such as the production or manufacture of goods. Volumes of industrial wastewater vary widely with the type of industry.^{[2]: 27â€ÅÂÂ}  Industrial wastewater may contain very different pollutants at much higher concentrations than what is typically found in sewage.^{[5]: 188â€ÅÂÂ}  Pollutants may be toxic or non-biodegradable waste including pharmaceuticals,^[29] biocides, heavy metals, radionuclides, or thermal pollution.

An industry may treat its wastewater and discharge it into the environment (or even use the treated wastewater for specific applications), or, in case it is located in the urban area, it may discharge the wastewater into the public sewerage system. In the latter case, industrial wastewater may receive pre-treatment at the factories to reduce the pollutant load.^{[2]: 27â€ÅÂÂ}  Mixing industrial wastewater with sewage does nothing to reduce the mass of pollutants to be treated, but the volume of sewage lowers the concentration of pollutants unique to industrial wastewater, and the volume of industrial wastewater lowers the concentration of pollutants unique to sewage.

When wastewater is discharged into a water body (river, lakes, sea) or land, its relative impact will depend on the assimilative capacity of the water body or ecosystem.^{[2]: 78â€ÅÂÂ}  Water bodies have a self-purification capacity, so that the concentration of a pollutant may decrease along the distance from the discharge point. Furthermore, water bodies provide a dilution to the pollutants concentrations discharged, although it does not decrease their mass. In principle, the higher the dilution capacity (ratio of volume or flow of the receiving water and volume or flow of sewage discharged), the lower will be the concentration of pollutants in the receiving water, and probably the lower will be the negative impacts. But if the water body already arrives very polluted at the point of discharge, the dilution will be of limited value.^[30]

In several cases, a community may partially treat its sewage, and still count on the assimilative capacity of the water body. However, this needs to be analyzed very carefully, taking into account the quality of the water in the receiving body before it receives the discharge of sewage, the resulting water quality after the discharge and the impact on the intended water uses after discharge. There are also specific legal requirements in each country. Different countries have different regulations regarding the specifications of the quality of the sewage being discharged and the quality to be maintained in the receiving water body.^{[2]: 152â€ÅÂÂ} The combination of treatment and disposal must comply with existing local regulations.

The assimilative capacity depends – among several factors – on the ability of the receiving water to sustain dissolved oxygen concentrations necessary to support organisms catabolizing organic waste.^{[19]: 9, 673â€ÅÂÂ}  For example, fish may die if dissolved oxygen levels are depressed below 5 mg/L.^{[31]: 573â€ÅÂÂ} 

Application of sewage to land can be considered as a form of final disposal or of treatment, or both.^{[2]: 189â€ÅÂÂ}  Land disposal alternatives require consideration of land availability, groundwater quality, and possible soil deterioration.^[32]

Sewage may be discharged to an evaporation or infiltration basin.^{[10]: 9–41â€ÅÂÂ}  Groundwater recharge is used to reduce saltwater intrusion, or replenish aquifers used for agricultural irrigation. Treatment is usually required to sustain percolation capacity of infiltration basins, and more extensive treatment may be required for aquifers used as drinking water supplies.^{[19]: 700–703â€ÅÂÂ} 

Sewage treatment is beneficial in reducing environmental pollution. Bar screens can remove large solid debris from sewage,^{[19]: 274–275â€ÅÂÂ}  and primary treatment can remove floating and settleable matter.^{[19]: 446â€ÅÂÂ}  Primary treated sewage usually contains less than half of the original solids content and approximately two-thirds of the BOD in the form of colloids and dissolved organic compounds.^[43] Secondary treatment can reduce the BOD of organic waste in undiluted sewage,^{[31]: 575â€ÅÂÂ}  but is less effective for dilute sewage.^[44] Water disinfection may be attempted to kill pathogens prior to disposal, and is increasingly effective after more elements of the foregoing treatment sequence have been completed.^{[19]: 359â€ÅÂÂ} 

An alternative to discharge into the environment is to reuse the sewage in a productive way (for agricultural, urban or industrial uses), in compliance with local regulations and requirements for each specific reuse application. Public health risks of sewage reuse in agriculture can be minimized by following a "multiple barrier approach" according to guidelines by the World Health Organization.^[45]

There is also the possibility of resource recovery which could make agriculture more sustainable by using carbon, nitrogen, phosphorus, water and energy recovered from sewage.^[46][4]

Sewage management includes collection and transport for release into the environment after a treatment level that is compatible with the local requirements for discharge into water bodies, onto soil, or for reuse applications.^{[2]: 156â€ÅÂÂ}  In most countries, uncontrolled discharges of wastewater to the environment are not permitted under law, and strict water quality requirements are to be met. For requirements in the United States, see Clean Water Act.

Sewage management regulations are often part of a country's broader sanitation policies. These may also include the management of human excreta (from non-sewered collection systems), solid waste and stormwater.

• Fecal sludge management
• History of water supply and sanitation
• Reuse of human excreta
• Urban Waste Water Treatment Directive
• Wastewater-based epidemiology

• Sanitation and Wastewater Atlas of Africa

Look up sewage in Wiktionary, the free dictionary.

Wikimedia Commons has media related to Wastewater.

Scholia has a topic profile for Sewage.