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Encyclopedia > Greywater

Greywater, sometimes spelled graywater, grey water or gray water and also known as sullage, is non-industrial wastewater generated from domestic processes such as washing dishes, laundry and bathing. Greywater comprises 50-80% of residential wastewater. Greywater is distinct from blackwater in the amount and composition of its chemical and biological contaminants (from feces or toxic chemicals). Greywater gets its name from its cloudy appearance and from its status as being neither fresh (white water from groundwater or potable water), nor heavily polluted (blackwater). According to this definition wastewater containing significant food residues or high concentrations of toxic chemicals from household cleaners etc. may be considered "dark grey" or blackwater. Wastewater is any water that has been adversely affected in quality by anthropogenic influence. ... Blackwater (waste) is a relatively recent term used to describe water containing Feacal matter and Urine: its is also known as foul water, or as sewage. ... Horse feces Feces, faeces, or fæces (see spelling differences) is a waste product from an animals digestive tract expelled through the anus (or cloaca) during defecation. ... Toxic redirects here, but this is also the name of a song by Britney Spears; see Toxic (song) Look up toxic and toxicity in Wiktionary, the free dictionary. ... The chemical industry comprises the companies that produce industrial chemicals. ... Missing main definition------ someone add if you know it please. ... Drinking water This article focuses on water as we experience it every day. ...

In recent years concerns over dwindling reserves of groundwater and overloaded or costly sewage treatment plants has generated much interest in the reuse or recycling of greywater, both domestically and for use in commercial irrigation. However, concerns over potential health and environmental risks means that many jurisdictions demand such intensive treatment systems for legal reuse of greywater that the commercial cost is higher than for fresh water. Despite these obstacles, greywater is often reused for irrigation, illegally or not, in older rural construction, simple construction old and new, often consisting of nothing more than a "drain out back" (pipe pointed down the nearest hill). In droughtzones or areas hit by hose pipe bans (irrigation restrictions) greywater can be harvested informally by manual bucketing. In the third world, reuse of greywater is often unregulated and is common. At present, the recycling of greywater is poorly understood compared with elimination. Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater, both runoff and domestic. ... This article needs additional references or sources to facilitate its verification. ... Irrigation is the artificial application of water to the soil usually for assisting in growing crops. ... Fields outside Benambra, Victoria, Australia suffering from drought conditions A drought is an extended period of months or years when a region notes a deficiency in its water supply. ... A hosepipe ban is a restriction placed on the customers of a water company to prevent them from using hosepipes, particularly for watering their gardens. ... For the Jamaican reggae band, see Third World (band). ...


Elimination of greywater

Domestic wastewater is usually combined at the sewer, so that grey and black waters are removed together using a shared sewerage system. Sewage water can then be treated to limit pollution and health risks, before being returned to the environment at large. The majority of greywater ends up as effluent in rivers and oceans in this way. Despite treatment, this arguably results in greater contamination of natural waters, as the natural purification capacity of surface water is millions of times less than that of soil. Simply dumping greywater on the soil, from an ecological standpoint, is less damaging than sending highly treated greywater directly into natural waters. A sewer is an artificial conduit or system of conduits used to remove sewage (human liquid waste) and to provide drainage. ... Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater, both runoff and domestic. ... In the context of creating Plutonium at the Hanford Site, effluent refers to the cooling water that is discharged from a nuclear reactor that may or may not be radioactive. ...

There has not been one documented case of greywater transmitted illness in the U.S.[1] This proves that the reuse of greywater is a safe way to conserve our natural water supply and keep natural freshwater free of contamination, and shows that the elimination of greywater is not the most efficient way to deal with it. Pouring greywater onto the soil is a better alternative to deal with it rather than pouring it down the drain because the soil acts as a natural filtration system. There are other alternatives to eliminating greywater that allow for efficient use; using it to irrigate plants is a common practice. The plants use the alleged contaminants of greywater, such as food particles, as nutrients in their growth.[3] Treating greywater before using it to irrigate plants is like treating water then pouring it into the drain, its a pointless practice. The elimination of greywater in sewage treatment plants is held low by many environmental conservationists because of its many possible uses and alternatives to elimination are highly recommended by online sources.[2]

Recycling of greywater

Most greywaters are much easier to treat and recycle than blackwaters, due to their lower levels of contamination. However, entirely untreated greywater is still considered to be a potential health and pollution hazard, because studies have established the presence of the same micro-organisms within greywater as found in sewage (albeit in much lower concentrations). Nevertheless, whilst all greywater will contain micro-organisms the health hazards associated with greywater from a multiple dwelling source should be considered different from that of a single dwelling greywater source. Within single dwellings inhabitants and their clothing are mutually exposed to each other's greywater and their shared living arrangements will likewise expose them to the existing reservoir of micro-organisms within the dwelling, whereas greywater from multiple dwelling sources provides scope for exposure to a broader reservoir of micro-organisms thus increasing the risk of disease spread between dwelling unit inhabitants.

If collected using a separate plumbing system to blackwater, domestic greywater can be recycled directly within the home and garden. Recycled greywater of this kind is never clean enough to drink, but a number of stages of filtration and microbial digestion can be used to provide water for washing or flushing toilets; relatively clean greywater may be applied directly from the sink to the garden, as it receives high level treatment from soil and plant roots. Given that greywater may contain nutrients (e.g. from food), pathogens (e.g. from your skin), and is often discharged warm, it is very important not to store it before using it for irrigation purposes, unless it is treated first. Recycled water is wastewater that has been recovered for potable or nonpotable use, such as reclaimed water. ... This article needs additional references or sources for verification. ...

There are numerous "soft" processes based on natural biological principles such as using reedbed filter systems, the wetpark systems or the living wall that can be used to clean up greywater. A reedbed in summer Reedbeds are basically ’temporary’ habitats. ... Green Wall at Queens University, Kingston, Ontario, Canada A living wall is a vertical garden. ...

There are also "hard", direct processes, such as distillation (evaporation) which need not necessarily be as energy intensive as they might initially appear. There seem to be no commercially available "hard" greywater recovery devices suitable for on-site use in the individual household, even though a number of such technologies exist.

Some municipal sewerage systems recycle a certain amount of grey and black waters using a high standard of treatment, thus providing reclaimed water for irrigation and other uses. Warning sign in Santa Monica, California, where reclaimed water is used to irrigate plants in public parks. ...

Application of recycled greywater


Greywater typically breaks down faster than blackwater and has much less nitrogen and phosphorus. However, all greywater must be assumed to have some blackwater-type components, including pathogens of various sorts. Greywater should be applied below the soil surface where possible (e.g. in mulch filled trenches) and not sprayed, as there is a danger of inhaling the water as an aerosol. General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, symbol, number phosphorus, P, 15 Chemical series nonmetals Group, period, block 15, 3, p Appearance waxy white/ red/ black/ colorless Standard atomic weight 30. ... A pathogen (literally birth of pain from the Greek παθογένεια) is a biological agent that can cause disease to its host. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland Technically, soil forms the pedosphere: the interface between the lithosphere (rocky part of the planet) and the biosphere, atmosphere, and hydrosphere. ...

However, long term research on greywater use on soil has not yet been done and it is possible that there may be negative impacts on soil productivity. If you are concerned about this, avoid using laundry powders; these often contain high levels of salt as a bulking agent, and this has the same effect on your soil as a drought.

Indoor reuse

Recycled greywater from showers and bathtubs can be used for flushing toilets, which saves great amounts of water. Many attempts at this have been made in Germany. However, untreated greywater cannot be used as flush-water as it will start to smell and discolor the flush toilet fixture if left for a day or more.

The level of treatment required in this case requires the water to have low or nil biochemical oxygen demand, but it is not necessary for it to be treated to the same standards as potable water. Greywater recycling for toilet flushing is currently considered to be uneconomical or environmentally unfriendly at most domestic levels. However, a Quebec company, Brac Systems, has recently patented a cost-effective system that uses a chlorine treatment, and is selling the system in the Americas, Europe, and Australia. As an alternative to treatment, a South African Company is manufacturing and distributing the GardenResQ product in both South Africa and Australia - a grey water diversion systems that allows all household grey water to be automatically diverted to the garden for irrigation purposes. This article or section does not cite any references or sources. ... , Motto: Je me souviens (French: I remember) Capital Quebec City Largest city Montreal Official languages French Government - Lieutenant-Governor Pierre Duchesne - Premier Jean Charest (PLQ) Federal representation in Canadian Parliament - House seats 75 - Senate seats 24 Confederation July 1, 1867 (1st) Area  Ranked 2nd - Total 1,542,056 km² (595... Brac Systems, Inc. ... General Name, symbol, number chlorine, Cl, 17 Chemical series halogens Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... World map showing the Americas CIA political map of the Americas The Americas are the lands of the Western hemisphere or New World consisting of the continents of North America[1] and South America with their associated islands and regions. ... For other uses, see Europe (disambiguation). ...

Extreme living conditions

Greywater use promotes the ability to build in areas unsuitable for conventional treatment, or where conventional treatment is costly. The Mars Desert Research Station utilizes greywater recycling for this use, and might be used on trips to Mars to reduce water consumption and increase oxygen generation. The Mars Desert Research Station (MDRS) is one of four planned simulated Mars habitats (or Mars Analogue Research Station) maintained by the Mars Society. ... Adjectives: Martian Atmosphere Surface pressure: 0. ...

Heat reclamation

Devices are currently available that capture heat from residential and industrial greywater, through a process called "Drainwater Heat Recovery" or "Greywater Heat Recovery." Rather than flowing directly into a water heating device, incoming cold water flows first through a heat exchanger where it is pre-warmed by heat from greywater flowing out from such activities as dishwashing, or showering. Typical household devices receiving greywater from a shower can recover up to 60% of the heat that would otherwise go to waste.

Greywater and the environment

The potential ecological benefits of greywater recycling include:

  • Lower fresh water extraction from rivers and aquifers
  • Less impact from septic tank and treatment plant infrastructure
  • Topsoil nutrification
  • Reduced energy use and chemical pollution from treatment
  • Groundwater recharge
  • Plant growth
  • Reclamation of otherwise misdirected nutrients

In the U.S. Southwest and the Middle East where available water supplies are limited, especially in view of a rapidly growing population, a strong imperative exists for adoption of alternative water technologies. The Southwest region of the United States is drier than the adjoining Midwest in weather; the population is less dense and, with strong Spanish-American and Native American components, more ethnically varied than neighboring areas. ... A map showing countries commonly considered to be part of the Middle East The Middle East is a region comprising the lands around the southern and eastern parts of the Mediterranean Sea, a territory that extends from the eastern Mediterranean Sea to the Persian Gulf. ...

Move towards ecologically sustainable development

Because greywater use, especially domestically, reduces demand on conventional water supplies and pressure on sewage treatment systems, its use is very beneficial. In times of drought, especially in urban areas, greywater use on gardens or in toilet systems helps to achieve Ecologically Sustainable Development by helping to meet its principles. It has been suggested that this article or section be merged with Sustainable development#Environmental Sustainability . ...

Governmental Regulation

Government regulation governing domestic greywater use for garden irrigation (diversion for reuse) is still a developing area and continues to gain wider support as the actual risks and benefits are considered and put into clearer perspective. Government regulation involves the use of the law, mandated by the state, to produce outcomes which might not otherwise occur, prevent outcomes which might otherwise occur, produce or prevent outcomes in different places to what might otherwise occur, or produce or prevent outcomes in different timescales than would otherwise occur. ...

'Greywater' (by pure legal definition) is considered in most jurisdictions to be 'Sewage’ (all wastewater including greywater and toilet waste) and under that definition greywater is commonly bound by the same regulatory procedures enacted to ensure properly engineered septic tank and effluent disposal systems are installed for long system life and to control spread of disease and pollution. In such regulatory jurisdictions this has commonly meant domestic greywater diversion for garden irrigation was either simply not permitted or was discouraged by expensive and complex governmental sewage system approval requirements. Wider legitimate community greywater diversion for garden irrigation has subsequently been handicapped and resulted in greywater reuse continuing to still be widely undertaken by householders outside of and in preference to the legal avenues, even when generous cash rebates have been offered by governments. A septic tank, the key component of a septic system, is a small scale sewage treatment system common in areas with no connection to main sewerage pipes provided by private corporations or local governments. ... Irrigation is the artificial application of water to the soil usually for assisting in growing crops. ...

However, with water conservation becoming a necessity in a growing number of jurisdictions, business, political and community pressure has made regulators seriously reconsider the actual risks against potential benefits. It is now recognized and accepted by an increasing number of regulators that the microbiological risks of greywater reuse at the single dwelling level where inhabitants already had intimate contact with that greywater are in reality an insignificant risk, if properly managed without the need for complex, expensive and onerous red tape approval processes. The most recent examples are reflected in the NSW Government Department of Water and Energy's newly released greywater diversion rules, and the recent passage of greywater legislation in the state of Montana.[3] Water conservation refers to reducing use of fresh water, through technological or social methods. ...

See also

The following page consist of a list of waste water treatment technologies: Activated sludge Anaerobic digestion Anaerobic lagoon Cesspit Combined sewer overflow Composting toilet Constructed wetland Imhoff tank Floculation Reed bed Septic tank Sequencing batch reactor UASB Aerobic Granular Reactor This list is incomplete; you can help by expanding it. ... Ecological Sanitation One person produces about 500 litres of urine and only 50 litres of faeces per year. ... E. Coli bacteria under magnification Sanitation is the hygienic disposal or recycling of waste, as well as the policy and practice of protecting health through hygienic measures. ... Sewage is the mainly liquid waste containing some solids produced by humans which typically consists of washing water, faeces, urine, laundry waste and other material which goes down drains and toilets from households and industry. ... Water conservation refers to reducing use of fresh water, through technological or social methods. ... Control room and schematics of the water purification plant to Bret lake. ... Recycled water is wastewater that has been recovered for potable or nonpotable use, such as reclaimed water. ...


  1. ^ [1]
  2. ^ [2] Oasisdesign.net]
  3. ^ "SAVE works for passage of graywater legislation", Shelby Promoter, 2007-05-02. Retrieved on 2007-05-09. 

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ...

External links

  Results from FactBites:
Greywater - Wikipedia, the free encyclopedia (739 words)
Greywater, sometimes also spelt as graywater, grey water or gray water and also known as 'sullage', is wastewater generated from processes such as washing dishes, laundry and bathing.
Despite this, greywater is often reused for irrigation, illegally or not, in drought zones or areas hit by hose pipe bans, typically by manual bucketting.
Greywater recycling for toilet flushing is generally not economical at a residential scale.
Sustainable Earth Technologies - Greywater Treatment (574 words)
Greywater can be defined as any domestic wastewater produced, excluding sewage.
The main difference between greywater and sewage (or flwater) is the organic loading.
The main advantage with these types of systems is that they treat the greywater naturally, and also enhance the local environment because of the attractive plants used and the fauna attracted to them.
  More results at FactBites »



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