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{{main|Portal:Greywater treatment}}
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'''Greywater''', '''grey water''' or '''gray water''', is water that has been polluted with (non-)biodegradable soaps and detergents.
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==Introduction==
'''Greywater''', sometimes also spelled as '''graywater''', '''grey water''' or '''gray water''', is all of the effluent water from a household, except that from the [[Toilet design|toilet]]s, which is sometimes called "blackwater". In addition, if greywater is held for too long (>24 hours in temperate climates), it will become blackwater.{{fact}} 


The water leaving our homes carries nutrients and value. It may also contain [[pathogens]], and/or harsh chemicals and care should be taken with it; however, it is not a great risk compared to blackwater ([[sewage]]).  
==Sources==
Greywater originates from sinks, baths, showers, and floor drains, and flows into effluent pipes throughout the house. [[Flush toilet]]s, if present, produce [[blackwater]].


Redirecting the water we use for tasks such as showering allows us to reclaim some of that value to grow plants and recharge the [[water table]]. It may be necessary to choose our [[soap]]s and [[detergent]]s more carefully, if we use the greywater for watering and fertilizing plants.
==Recycling==
It is important to treat greywater separatly from blackwater, as the first is less polluted and so requires less treatment steps. By having less quantity of water going through less treatment steps the treatment procudure becomes more efficient and less costly.
 
It may be necessary to choose our [[soap]]s and [[detergent]]s more carefully (opting for bio-degradable soaps/detergents), if we use the greywater for watering and fertilizing plants (see Water recycling systems without purification).
 
===Systems===
{{See also|Water purification|Ecological sanitation}}
At present, several water recycling systems exist which can be used to:
* recycle the water without purifying it
* recycle the water while [[Water purification|purifying]] or decontaminating it
 
====Water recycling systems without purification====
Water recycling without purification is used in certain agricultural companies (e.g., tree nurseries) and [[dwellings]] for applications where potable water is not required (e.g., garden and land irrigation, toilet flushing). It may also be used in dwellings when the greywater (e.g., from [[Rainwater harvesting|rainwater]]) is already fairly clean to begin with and/or has not been polluted with non-degradable chemicals such as non-natural soaps (thus using natural cleaning products instead).
This water system also needs a supply of water to recycle and reuses water as well.  It is also not recommended to use water that has been in the greywater filtration system for more than 24 hours or bacteria builds up affecting the water that is being reused.
 
====Water recycling with purification====
Water purification/decontamination systems are used for applications where potable water ''is'' required (e.g., to allow [[drinking]], and/or for other [[Home|domestic]] tasks as [[washing]], [[showering]]).
 
For filtering the water to become potable (or near-potable), there are numerous systems based on ''soft'' processes. These include [[Biofilter|natural biological principles]] such as
* mechanical systems ([[sand filter|sand filtration]], [[lava filter|lava filter systems]] and systems based on [[UV]] radiation)
* biological systems (plant systems as [[treatment pond]]s, [[constructed wetlands]]<ref>From the book "Guide to greywater": 1 <math>ft^3</math> of Constructed Wetland for every 1 gallon of graywater per day. This must be with a maximum two foot depth, especially considering that Oasis Design states 1/2 to 1 square foot for every 1 gallon of graywater per day</ref>, [[living wall]]s) and Bio reactors or compact systems as [[Activated sludge|activated sludge systems]], biorotors, [[aerobic biofilter|aerobic]] and [[anaerobic biofilters]], submerged aerated filters, biorolls <ref>[http://www.oost-vlaanderen.be/docs/nl/gc/35447.%20afvalwaterzuivering%20op%20landbouwbedrijven.pdf Overview of biological systems with pictures]</ref>
 
Finally, "hard", direct processes, such as [[distillation]] (evaporation) or mechanical processes such as [[Membrane technology|membrane filtration]], (typically [[ultrafiltration]] and [[reverse osmosis]], which are capable of treating high volumes of grey water) can create potable, or near-potable water.  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.
 
In order to purify the potable water adequately, several of these systems are usually combined to work as a whole. Combination of the systems is done in two to three stages, using a [[Primary water purification|primary]] and a [[Secondary water purification|secondary purification]]. Sometimes a tertiary purification is also added.
 
Some municipal sewage systems recycle a certain amount of grey and blackwater using a high standard of treatment, providing [[reclaimed water]] for irrigation and other uses.
 
==Advantages and disadvantages==
Both the water itself as well as the nutrients inside the greywater is of value. This as water is an increasingly limited resource (especially in dry climates). Redirecting the pure water we use for tasks such as showering allows us to reclaim some of that value to grow plants and recharge the [[water table]].
 
By using greywater systems to reuse drained wash water to flush [[toilet]]s or to water lawns and [[garden]]s, we can halve the water use of most residential buildings.
 
Greywater systems may however require the purchase of a sump, greywater pressurization pump and secondary [[plumbing]].


==Tips on how to minimize health risks associated with greywater==
* Wash yourself after contacting greywater.
* Install signage around greywater [[irrigation]] systems or areas.
* Do not drink or play with greywater.
* Do not allow anything that may be eaten to come into contact with greywater.
* Do not allow greywater to pond or run off the property.
* Do not wash domestic [[pets]] in greywater or allow pets to drink greywater.
* Do not use greywater in public places such as children's play areas or playgrounds, BBQ areas or recreation facilities.
==Suggested projects==
==Suggested projects==
* What is the effect of various detergents and soaps in a greywater system? Consider the receiving soil and plant types - the answer may vary.{{sp}}
* What is the effect of various detergents and soaps in a greywater system? Consider the receiving soil and plant types - the answer may vary.{{sp}}
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==Projects==
==Projects==
*The old [http://www.humboldt.edu/~ccat/waterconservation/marsh/index.html greywater] system at [[:Category:CCAT|CCAT]]
*[http://www.humboldt.edu/ccat/waterconservation/marsh/index.html The old greywater system] at [[:Category:CCAT|CCAT]]


==Interwiki links==
== Footnotes ==
{{reflist}}
 
 
==See also==
*[[Earthship]]: domestic water system
 
==External links==
* [http://peswiki.com/index.php/Directory:Home_Generation:Gray_Water_Recycling Grey water recycling systems]
* [[Greenlivingpedia:Knoxfield house#Greywater System|Knoxfield greywater system]] - application of greywater treatment in a house in Knoxfield, in the suburbs of [[Melbourne]], [[Australia]]. - ''Greenlivingpedia''
* [[Greenlivingpedia:Knoxfield house#Greywater System|Knoxfield greywater system]] - application of greywater treatment in a house in Knoxfield, in the suburbs of [[Melbourne]], [[Australia]]. - ''Greenlivingpedia''
*[http://www.owue.water.ca.gov/docs/graywater_guide_book.pdf The graywater guide book from January 1995 (pdf)]
* [http://www.greywater.com/ Greywater.com] - design information and diagrams.
* [http://www.graywater.net/ Oasis Designs], greywater information resource
* [http://www.oasisdesign.net/greywater/misinfo/index.htm Common Grey Water Errors and Preferred Practices]. "An ongoing effort to counter the tidal wave of grey water misinformation on the web." Oasis Designs (commercial site).
* [http://agroforestry.net/overstory-back-issues/44-overstory-99-greywater-for-trees-and-landscape Greywater for Trees and Landscape] by Art Ludwig on agroforestry.net.
* [http://cahe.nmsu.edu/pubs/_m/m-106.html Safe Use of Household Greywater], College of Agriculture and Home Economics New Mexico State University.
* [[Wikipedia:Greywater]]
* [[Wikipedia:Greywater]]
==External links==
*[http://www.graywater.net/ Oasis Designs] - The best [http://www.oasisdesign.net/greywater/misinfo/index.htm common errors and best practices] section ever.
*The [http://epa.gov/water/ EPA] on water.
*[http://agroforestry.net/overstory/overstory99.html Agroforestry] on greywater for Trees and Landscape.
*http://www.greywater.com/ - Check out their [http://www.greywater.com/pollution.htm pollution] page.
*[http://cahe.nmsu.edu/pubs/_m/m-106.html College of Agriculture and Home Economics New Mexico State University]
*[http://www.latimes.com/features/home/la-hm-graywater29mar29,0,7773709.story 3/29/07 LA Times article on Grey water's red tape]
*[http://www.owue.water.ca.gov/docs/graywater_guide_book.pdf The graywater guide book from January 1995 (pdf)] 
**Focuses on Subsurface Drip Irrigation and Mini-Leachfield in California
*[http://www.owue.water.ca.gov/docs/Revised_Graywater_Standards.pdf 1997 Revised California Graywater Standards (pdf)] 
**Main changes:
*#Use in commercial, industrial and multifamily projects is now acceptable  (and procedures for estimating discharge in those environments are now included). Whereas before only single family homes were allowed.
*#One irrigation zone is now acceptable.  Whereas before two were required.
*#Filters are now sized based on filtration rate.  Whereas before a 1 inch filter was prescribed.
*[http://www.p2pays.org/ref/18/17818.htm California Revised Greywater Code (html)]
*[http://www.ext.colostate.edu/pubs/natres/06702.html Colorado State University - Greywater information]
*[http://weblife.org/humanure/chapter9.html Chapter 9 of the Humanure Handbook]
*[http://www.self-sufficiency-guide.com/Greywater.html Guide to Greywater]
**Excellent resource.  Punchline: 1 <math>ft^3</math> of Constructed Wetland for every 1 gallon of graywater per day. This must be with a maximum two foot depth, especially considering that Oasis Design states 1/2 to 1 square foot for every 1 gallon of graywater per day.
*[http://www.p2pays.org/ref/12/11609.pdf Texas A&M Greywater]
**Great pictures


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[[Category:Greywater]]
[[Category:Wastewater]]
[[Category:Wastewater]]
[[Category:Sewage]]
[[Category:Sewage]]

Revision as of 03:46, 25 November 2016

Template:Topic with portal header

Greywater, grey water or gray water, is water that has been polluted with (non-)biodegradable soaps and detergents.

Sources

Greywater originates from sinks, baths, showers, and floor drains, and flows into effluent pipes throughout the house. Flush toilets, if present, produce blackwater.

Recycling

It is important to treat greywater separatly from blackwater, as the first is less polluted and so requires less treatment steps. By having less quantity of water going through less treatment steps the treatment procudure becomes more efficient and less costly.

It may be necessary to choose our soaps and detergents more carefully (opting for bio-degradable soaps/detergents), if we use the greywater for watering and fertilizing plants (see Water recycling systems without purification).

Systems

At present, several water recycling systems exist which can be used to:

  • recycle the water without purifying it
  • recycle the water while purifying or decontaminating it

Water recycling systems without purification

Water recycling without purification is used in certain agricultural companies (e.g., tree nurseries) and dwellings for applications where potable water is not required (e.g., garden and land irrigation, toilet flushing). It may also be used in dwellings when the greywater (e.g., from rainwater) is already fairly clean to begin with and/or has not been polluted with non-degradable chemicals such as non-natural soaps (thus using natural cleaning products instead). This water system also needs a supply of water to recycle and reuses water as well. It is also not recommended to use water that has been in the greywater filtration system for more than 24 hours or bacteria builds up affecting the water that is being reused.

Water recycling with purification

Water purification/decontamination systems are used for applications where potable water is required (e.g., to allow drinking, and/or for other domestic tasks as washing, showering).

For filtering the water to become potable (or near-potable), there are numerous systems based on soft processes. These include natural biological principles such as

Finally, "hard", direct processes, such as distillation (evaporation) or mechanical processes such as membrane filtration, (typically ultrafiltration and reverse osmosis, which are capable of treating high volumes of grey water) can create potable, or near-potable water. 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.

In order to purify the potable water adequately, several of these systems are usually combined to work as a whole. Combination of the systems is done in two to three stages, using a primary and a secondary purification. Sometimes a tertiary purification is also added.

Some municipal sewage systems recycle a certain amount of grey and blackwater using a high standard of treatment, providing reclaimed water for irrigation and other uses.

Advantages and disadvantages

Both the water itself as well as the nutrients inside the greywater is of value. This as water is an increasingly limited resource (especially in dry climates). Redirecting the pure water we use for tasks such as showering allows us to reclaim some of that value to grow plants and recharge the water table.

By using greywater systems to reuse drained wash water to flush toilets or to water lawns and gardens, we can halve the water use of most residential buildings.

Greywater systems may however require the purchase of a sump, greywater pressurization pump and secondary plumbing.

Suggested projects

  • What is the effect of various detergents and soaps in a greywater system? Consider the receiving soil and plant types - the answer may vary.[expansion needed]

Organizations

Projects

Footnotes

Template:Reflist


See also

External links

Template:Stub Template:Topicadmin

  1. From the book "Guide to greywater": 1 of Constructed Wetland for every 1 gallon of graywater per day. This must be with a maximum two foot depth, especially considering that Oasis Design states 1/2 to 1 square foot for every 1 gallon of graywater per day
  2. Overview of biological systems with pictures
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