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. Sometimes, the term excludes kitchen wastewater containing significant food residues. It is quite distinct from blackwater in the amount and composition of its chemical and biological contaminants. Greywater gets its name from its appearance and possibly also from its status as neither being fresh (groundwater or potable water), nor heavily polluted (blackwater). From the point of view of treatment and pollution prevention, greywater decomposes much more quickly and is easier to treat and eliminate than blackwater, but is still considered to be a health and pollution hazard if released into the natural environment untreated. A kitchen is a room used for food preparation. ... 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. ... Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of geologic formations. ... 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 reusing or recycling greywater, particularly for use in irrigation. However, concerns over potential health and environmental risks means that many jurisdictions demand intensive treatment systems that are so expensive they usually cost more than simply treating and buying the tap water they save. Treatment methods and risks are poorly researched and understood by authorities. 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. In the third world, reuse of greywater is often unregulated and is common. At present, the recycling of greywater and its risks are poorly researched compared with its elimination. Sewage (or domestic wastewater) treatment incorporates physical, chemical and biological processes which treat and remove physical, chemical and biological contaminants from water following human use. ...   The international symbol for recycling. ... High-altitude aerial view of irrigation in the Heart of the Sahara (, ) Irrigation (in agriculture) is the replacement or supplementation of rainfall with water from another source in order to grow crops. ... A drought or an extreme dry periodic climate is an extended period where water availability falls below the statistical requirements for a region. ... 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). ...

Reuse of Greywater

Greywater comprises 50-80% of residential "waste" water. It may be reused for other purposes, especially landscape irrigation (see http://greywater.net). The benefits of grey water reuse can include:

• Lower fresh water use
• Less strain on failing septic tank or treatment plant
• Grey water treatment in topsoil is highly effective
• Ability to build in areas unsuitable for conventional treatment
• Less energy and chemical use
• Groundwater recharge
• Plant growth
• Reclamation of otherwise wasted nutrients

Greywater typically breaks down faster than blackwater and has much less nitrogen and phosphorous -- see http://www.greywater.com. However, all greywater must be assumed to have some blackwater-type components, including pathogens of various sorts.

Blackwater from the household and other venues can be eliminated via the application of commercially available composting or incinerating toilets in place of the classical flush toilet. Similar devices can be used to dispose of garbage from the kitchen sink disposal.

With appropriate plumbing, greywater can be used for irrigation without pretreatment (it receives high level treatment from soil and plant roots). 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.

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. ... A living wall or Folkewall 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 as yet no commercially available "hard" greywater recovery devices suitable for on-site use in the individual household, even though a number of such technologies exist, thanks, for example, to the space programs.

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. Although the level of treatment required in this case requires the water to have low or nil BOD, it is not necessary for it to be treated to the same standards as potable water. Greywater recycling for toilet flushing is generally not economical at a residential scale. Boeing 747 toilet A toilet is a plumbing fixture and a disposal system primarily intended for the disposal of the bodily wastes; urine, fecal matter, vomit and menses. ... Look up bod in Wiktionary, the free dictionary. ... Drinking water This article focuses on water as we experience it every day. ...

In the water damage restoration industry, grey water is considered to be any water from the exterior of the home, or clean water that has been standing for more than 48 hours.

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. See the Greywater Policy Center, http://oasisdesign.net/greywater/law/index.htm .
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. ...

Waste inside a rubbish bin Waste, rubbish, or garbage is unwanted or undesired material. ... A compost bin full of autumn oak leaves Compost is the decomposed remnants of organic materials (those with plant and animal origins). ... A dustbin is a container used to store refuse which can be made out of metal or plastic¹. Other names include trash can, garbage can and trash bin. ... Abandoned monitor Electronic waste or e-waste is any broken or unwanted electrical or electronic appliance. ... A typical front loader garbage truck in North America A garbage truck in US English; or dustcart, or sometimes dustbin wagon in Commonwealth English, is a truck specially designed to haul waste to landfills and other recycling / disposal facilities. ... Garbology is the study of refuse and trash. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Landfill is a waste disposal site for the deposit of the waste onto or into land (i. ... Water pollution Pollution is the release of environmental contaminants. ... Radioactive waste is waste material containing radioactive chemical elements that does not have a practical purpose. ...   The international symbol for recycling. ... The international symbol for recycling. ... Sewage includes domestic, municipal, or industrial liquid waste products disposed of via a pipe or similar structure. ... A scrapyard Scrap is a term used to describe the recycling of metal. ... Sewage (or domestic wastewater) treatment incorporates physical, chemical and biological processes which treat and remove physical, chemical and biological contaminants from water following human use. ... This page meets Wikipedias criteria for speedy deletion. ... Toxic waste is a waste which is toxic for a variety of reasons. ... Waste management is the collection, transport, processing or disposal of waste materials, usually ones produced by human activity, in an effort to reduce their effect on human health or local aesthetics or amenity. ...

See also

• Night Soil

Night soil is a term most often used to describe the practice of using untreated human waste as fertilizer. ...

External links

• Greywater Recycling Information Url accessed May 11, 2006