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E millcreekgreywater plant.JPG    More information is at Greywater category -
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Greywater, grey water or gray water, is water that has been polluted with (non-)biodegradable soaps and detergents.


[edit] Sources

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

[edit] 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).

[edit] Systems


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

[edit] Water recycling systems without purification


[edit] Water recycling with purification



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.



[edit] 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 however require the purchase of a sump, greywater pressurization pump and secondary plumbing.

[edit] 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.[Suggested project]

[edit] Organizations

[edit] Projects

[edit] Footnotes

  1. From the book "Guide to greywater": 1 ft^3 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

[edit] See also

[edit] External links


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