sewage sewage 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.: 175 sewage consists of wastewater discharged from residences and from commercial, institutional and public facilities that exist in the locality.: 10 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. this article is about a type of wastewater. for the infrastructure to transport sewage, see sewerage. part of a series onpollutionair pollution from a factory air acid rain air quality index atmospheric dispersion modeling chlorofluorocarbon exhaust gas haze indoor air internal combustion engine global dimming global distillation ozone depletion particulates persistent organic pollutant smog aerosol soot volatile organic compound biological biological hazard genetic 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 land water air rail sustainable transport urban sonar marine mammals and sonar industrial military abstract noise control radiation actinides bioremediation depleted uranium nuclear fission nuclear fallout plutonium poisoning radioactivity uranium electromagnetic radiation and health radioactive waste soil agricultural herbicides manure waste 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firewater freshwater groundwater hypoxia industrial wastewater marine debris monitoring nonpoint source see misc section nutrient ocean acidification oil spill pharmaceuticals freshwater salinization septic tanks sewage septic tanks pit latrine shipping stagnation sulfur water surface runoff turbidity urban runoff water quality misc point source area source legacy pollution lists diseases law by country most polluted cities least polluted cities by pm2.5 treaties categories by country environment portal ecology portal 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 of 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.: 20 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.: 33 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). in order to quantify the organic matter, indirect methods are commonly used: mainly the biochemical oxygen demand (bod) and the chemical oxygen demand (cod).: 36 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.: 156 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. terminology sewage and wastewater sewage (or domestic wastewater) consists of wastewater discharged from residences and from commercial, institutional and public facilities that exist in the locality.: 10 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.: 21 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. to be precise, wastewater is a broader term, because it refers to any water after it has been used in a variety of applications.: 1 thus it may also refer to "industrial wastewater", agricultural wastewater and other flows that are not related to household activities. blackwater this section is an excerpt from blackwater (waste). blackwater in a sanitation context denotes wastewater from toilets which likely contains pathogens that may spread by the fecal–oral route. blackwater can contain feces, urine, water and toilet paper from flush toilets. blackwater is distinguished from greywater, which comes from sinks, baths, washing machines, and other kitchen appliances apart from toilets. greywater results from washing food, clothing, dishes, as well as from showering or bathing. blackwater and greywater are kept separate in "ecological buildings", such as autonomous buildings. recreational vehicles often have separate holding tanks for greywater from showers and sinks, and blackwater from the toilet. greywater this section is an excerpt from greywater. greywater (or grey water, sullage, also spelled gray water in the united states) refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater from toilets. sources of greywater include sinks, showers, baths, washing machines or dishwashers. as greywater contains fewer pathogens than blackwater, it is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape or crop irrigation, and other non-potable uses. greywater may still have some pathogen content from laundering soiled clothing or cleaning the anal area in the shower or bath. the application of greywater reuse in urban water systems provides substantial benefits for both the water supply subsystem, by reducing the demand for fresh clean water, and the wastewater subsystems by reducing the amount of conveyed and treated wastewater. treated greywater has many uses, such as toilet flushing or irrigation. pumping station lifting sewage to the treatment plant in bujumbura, burundi greywater (a component of sewage) in a settling tank overall appearance the overall appearance of sewage is as follows:: 30 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.: 9–38 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.: 57 pollutants 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.: 28 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. the suspended and dissolved solids include organic and inorganic matter plus microorganisms.: 28 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.: 9–38 organic matter 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.: 35 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).: 35 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).: 36 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.: 55 typical values for physical–chemical characteristics of raw sewage is provided further down below. nutrients 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.: 77 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.: 43 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.: 45 pathogens human feces in sewage may contain pathogens capable of transmitting diseases.: 9–38 the following four types of pathogens are found in sewage: bacteria like salmonella, shigella, campylobacter, or vibrio cholerae; viruses like hepatitis a, rotavirus, coronavirus, 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).: 52 solid waste screening of the sewage with bar screens at a sewage treatment plant to remove larger objects in norton, zimbabwe screening of sewage at a sewage treatment plant in bujumbura, burundi 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. adults may be tempted to dispose of toilet paper, wet wipes, diapers, sanitary napkins, tampons, tampon applicators,