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Commercial information[edit]

Under "Indoor reuse" there is some commercial information about greywater treatment. As must be expected this is very, very incomplete, and should be removed. A much more general information could be provided. This could be:

Greywater, being only slightly polluted but representing the larger part of a household's wastewater, can be easily treated and reused in single or apartment houses, offices or tourism facilities, thus tremendously reducing freshwater demand. Greywater uses can be toilet flushing, garden irrigation, outdoor uses, but also laundry and even showering. The treatment technique and the quality of the treated greywater will have to be adapted to the reuse purposes. Normally greywater is collected seperately in each building or group of connected buildings, treated in a decentralised system and fed into a supply network for service water in the same building. There are a wide range of decentralised treatment techniques and ready made treatment devices available worldwide, not all being marketed in all countries. Among the most successful techniques are sequencing batch reactors (SBR), membrane bio-reactors (MBR), constructed wetlands (CW) and similar systems. For marketed devices see a list below. Successful examples include an apartment building in the Klosternga in Olso, the office buildings of the KFW and the GTZ in Frankfurt, the Arabella hotel in Offenbach, or apartment buildings in Berlin. Many other examples can be found on the internet.

List of marketed systems
List the ones already presented in the text
Add for example (and invite others to add their links):
Busse (MBR)
Pontos (SBR)


The thing about carpeting seems absurd. I'm taking it out for the time being - anyone have any information? Hardwick

No, but I agree with you.


I have started a cleanup and extension of this article. My plan is basically to have introduction, description and 'how it is reused' sections. I also suggest that a section on the plumbing aspect be included because greywater uses distinctly different plumbing from blackwater.--ChrisJMoor 03:32, 28 January 2006 (UTC)

It's going well, but I've added a cleanup tag for now, to get more attention onto it from editors. I've just created Water conservation, which links here.
It seems that there's not much else on Wikipedia about reuse of wastewater - the reuse section of the wastewater article could be expanded, or perhaps a separate article started. --Singkong2005 02:24, 8 May 2006 (UTC)

Septic tanks[edit]

I thought greywater was the water in septic tanks. Say explicitly if true or not. --—Preceding unsigned comment added by (talkcontribs)

I would say it is true and if not then that is where it belongs. What do your think about, greywater being used for fake snow? --—Preceding unsigned comment added by (talkcontribs)
My greywater tank comes from the bath/shower and kitchen/bathroom sinks. The kitchen sink goes via a grease trap to remove the grease from washing up (it gets pumped out every 3 months or so and disposed of). The greywater gets pumped out every day into my acreage yard. The septic tank is ONLY hooked up to the toilets and settles out before gravity feeding into a soakaway pit.
So no, greywater isn't necessarily in septic tanks.--—Preceding unsigned comment added by (talkcontribs)
Australian laws define grey water as non-toilet - ie no faeces. However, the laws also say we may only use grey water from showers, bathroom handbasins and laundries. We may not use water from kitchens because people use caustic dishwashing powder, and because the volume of solids is so much higher than the other sources. Our native plants also die if fed phosphates, so we must use nil-phosphorous or very low phosphorous laundry powders. Another issue is that we can't release grey water above ground. This minimises human contact. See Art Ludwig's site below. {{--Richardh9935 11:05, 16 September 2006 (UTC)richardh9935}}

Greywater is generally defined as anything not coming from the toilet. In recycling practice however, the water from the kitchen sink, dishwasher, and bathroom sinks is considered to be too "dirty" to reuse for the volumes of water produced, and is usually not captured for recycling, leaving bath water and laundry water as your best options. (Highest volume of water, lowest amount of contaminants.) Hope that helps. Crockspot 13:28, 16 September 2006 (UTC)

I am an Environmental Health Officer responsible for enforcing provisions surrounding waste water treatment systems. No, grey water is not water found in a septic tank. Packaged treatment plants tend to combine both black and grey water treatment to a secondary degree. However, traditional septic tanks should only be supplied with black water, since the introduction of grey water and its associated chemicals interferes with the microbial action that is designed to occur within the tank.

Living Walls[edit]

The article on Living Walls is somewhat lackluster but it still does say that these walls can be used to clean greywater. At the end of this article a section should be added with a link to the living wall article.

Grey Water vs. Greywater[edit]

The single word Greywater looks weird to me; Grey Water looks comfortable, so I checked with Google.

"Grey Water" gets about 590,000 hits compared with 366,000 for "Greywater". "Gray Water" gets fewer hits than either, but far more than "Graywater". It appears the world agrees with me, but not strongly.

Any objection to changing the article to consistently use 'Grey Water' as the main term? --—Preceding unsigned comment added by Jamie Lokier (talkcontribs)

You're right about google hits. I prefer greywater - maybe something to do with being a chemical engineer, that we make our common terms, such as "flowrate" into a single word. But Wikipedia isn't a specialist's resource, and it appears either is acceptable so I wouldn't object to a move. --Singkong2005 (t - c - WPID) 13:42, 21 June 2006 (UTC)

I work in the industry, and "greywater", "grey water", "graywater", and "gray water" are all commonly used. I personally use "greywater". Crockspot 13:22, 16 September 2006 (UTC)

Hazards of greywater[edit]

The article states in the first paragraph “greywater … is still considered to be a health and pollution hazard if released into the natural environment untreated”. What are the threats to health? I am storing water from my worm farm (it smells a bit) and would like to know whether handling this water and putting it on the garden is unhealthy.

Gg39au 20:44, 12 October 2006 (UTC)

I'm just responding to this because nobody else has responded quickly and not because I'm an expert. I assume you have a worm farm as a hobby or to dispose of kitchen scraps. Your worm water is probably smelly because you are storing it and it is becoming anerobic. Use it at once and it should not present any greater risk than water that percolates from pot plants and composting containers. The water may present a greater health risk if you put kitchen scraps into your wormery, although this is probably negligible if you only put scraps of veg/teabags/paper into it.
How much water are you getting from this worm farm anyway? If you are putting it into the garden simply to dispose of it, you can probably just water the worm farm less and have less to worry about.--ChrisJMoor 01:41, 19 November 2006 (UTC)

Moved from main page:

Continual discharge of incorrectly managed greywater can lead to cesspool conditions promoting the outbreak of Giardia in the community. In the past, outbreaks of Giardia have been the catalyst for local authorites expanding their sewage systems and improving the community health. Combined with this there is the added risk of food matter in kitchen wastewater providing breeding conditions for vermin.

I've not read anything about a connection between domestic or industrial greywater use and giardia contamination occurring in the community - the greywater would have to contaminate the municipal drinking water supply. Please re-add this content if suitable referencing can be provided.Natronomonas 22:57, 2 January 2007 (UTC)

Has anyone noticed that the article says because of bacteria you should both store greywater before use, and also use it within a day?

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.

Given that greywater may contain nutrients, pathogens, and is often discharged warm, it is very important to store it before use in irrigation purposes

Now, I don't know about you, but I find that a bit contradictory JBel (talk) 19:21, 2 May 2012 (UTC)

My article[edit]

Can I add a link to this article on cheap ways to use greywater?

Ozfreediver 07:07, 10 February 2007 (UTC)


This article needs to cite some sources. The governmental stuff an anon has been adding is great info, but we need sources. I added one to the end, to support the statement about a new law signed into effect in Montana. - Greywater 14:59, 9 May 2007 (UTC)

Remove section[edit]

In my edit [1], I removed the section entitled "Tips on how to minimize health risks associated with greywater", because I think it violates WP:NOT#GUIDE -- 15:34, 17 July 2007 (UTC)

I copied that deleted content to Appropedia as it fits the purpose of that wiki. I also added a link to the site under external links. Thank you, --LRG 02:16, 23 July 2007 (UTC)

what about soap?[edit]

Are soap and detergents safe to discharge onto plants or soil? -- 18:06, 27 October 2007 (UTC)

I'm trying to find information about this as well, and I suspect you would have to consider carefully what soaps and detergents and what else goes out in the "greywater". But I haven't been able to find any information on the topic yet.
Apis (talk) 20:15, 14 November 2008 (UTC)

Definition of Greywater[edit]

The definition of the expression refers to a colour which has become commonly used for this type of slghtly polluted used water. Due to the fact that the same words have been used in legislation, in the text of the laws of many countries, it is preferable to use the same denomination in other languages. In countries where precipitaion is scarce there are legal ragulations at the highest level in the form of greywater laws. (in many states of the USA, in Australia). In Germany, the equivalent of grey [Grauwasser]is used, too, for the definition of the same notion, for the description of slghtly polluted used water. In the majority of countries, however, this notion is not in the public knowledge. Therefore, in countries where this notion is not known by the general public, on introducing this notion it is preferable to use the distinct denomination and mirror translation of greywater, using the same term, for the sake of exactness and accuracy.

The "California gray water law" is considered to be the strictest one of all the national grey water laws. It defines grey water as follows:

"Graywater is untreated waste water which has not come into contact with toilet waste. Graywater includes waste water from bathtubs, showers, bathroom wash basins, clothes washing machines, and laundry tubs, or an equivalent discharge as approved by the Administrative Authority. It does not include waste water from kitchen sinks, photo lab sinks, dishwashers, or laundry water from soiled diapers."

It can be seen that grey does not mean the colour of the water, but rather it means the quality of this type of slightly polluted used water. It is interesting to see that waste water from kitchen sinks does not qualify as grey water, it is already considered as "black water", because it may contain food remains and it is greasy, so it might contain a higher count of bacteria.

The most important criteria for reusing grey water are the following: Grey water can be reused only after filtering and disinfection. There are two types of grey water: 1. rainwater is considered a lighter grey water, because it does not contain so much contaminants, only leaves, feathers and other contaminants from birds. We can use rainwater to water the garden and food plants, and to wash the car. The darker grey water is washing-water from the bath tub and from the washing machine, and that darker type needs more treatment, i.e. filtering and disinfecting, following which grey water can be used to flush the toilet. This darker type of household greywater from washing can be used for watering food plant only in case it contains bio-degradeable detergents. Otherwise, food plants can not be irrigated by gray-water conaminated by not biodegradable detergents and soaps. (for more info and suggested domestic reuse of grey-water, please, visit:

Neutrality notice[edit]

Does anybody know the history behind the Neutrality Notice that someone inserted back in 2007? Aside from the lack of apparent discussion here, it doesn't look like there is a basis for keeping that notice in place.--Coro (talk) 21:19, 28 August 2009 (UTC)

I agree. I think the article needs improving but it doesn't seem particularly biassed. I'll remove it. Chris55 (talk) 11:10, 19 January 2010 (UTC)


THIS ARTICLE IS A COPYRIGHT VIOLATION SEE HERE: [2] ☻☻☻Sithman VIII !!☻☻☻ 16:47, 21 November 2010 (UTC)

It's not a copyright violation - it's recycling. — Preceding unsigned comment added by (talk) 23:19, 16 November 2011 (UTC)

Someone please consider adding these links[edit]

Hi, Oasis Design here, greywater advocates/ educators/ researchers.

We'd like to respond to the plea to improve the organization and referencing of this article. There are various references to information on our own site that could be beneficial to Wikipedia readers and appropriate within all external link guidelines ([links])--provided we do not post the links ourselves. (Someone posted ours as the top link on the appropedia greywater wiki page, where it's been unchallenged since as far back as the edit history goes [2006]).

Would you please take a look at these links and post any that you think have merit?

Possible external link: Grey Water Information Central

Possible references: Gray Water Policy Center {under "Governmental regulation"} Greywater risk calculations and references {under "Recycling/ hazards associated with greywater} Open Source Laundry to Landscape Greywater System {under "Garden irrigation water diversion systems/Laundry to Landscape" Common greywater Mistakes and Preferred Practices {under various locations, for example indoor reuse, health issues...}

Thanks Gwguru (talk) 21:10, 10 December 2010 (UTC)

Discover (magazine) resource[edit]

Are Americans Ready to Start Drinking Their (Treated) Toilet Water? "Tests show it's impressively clean and safe. And good enough for Texans who are drinking it." by Elizabeth Svoboda, from the November 2011 issue; published online October 28, 2011 Discover (magazine).

Also current (December 2011) issue cover story is "Water Wars: The coming battle over Earth's most precious resource ... The Future of Water", starting page 48 with Heidi Cullen for Climate Central, Bill Richardson on World Resources Institute, Grady Gammage Jr. attorney with Arizona State University Global Institute of Sustainability, and Pat Mulroy of the Southern Nevada Water Authority. Past notice

See Planetary boundaries. (talk) 00:08, 10 November 2011 (UTC)

Image removal[edit]

I deleted the photo at the top right because my friend requested that she not have that picture of her there... It was not exactly kosher. — Preceding unsigned comment added by (talkcontribs) 22:50, 29 November 2011‎

No problem. I've restored a cropped version of it, as the rest of the picture seems useful. --McGeddon (talk) 09:53, 30 November 2011 (UTC)
Hey guys I solved it better and just put up a different photo with all parts of the system. --David Shankbone 02:47, 23 December 2011 (UTC)

Why does self-evident material need citation?[edit]

In the article I read: "Greywater typically breaks down faster than blackwater and has lower levels of nitrogen and phosphorus[citation needed]. " Now , I don't know whether the intention was: "Greywater typically breaks down faster than blackwater[citation needed] and has lower levels of nitrogen and phosphorus." which I suppose would be reasonable, but as it stands citation demand suggests that the citation must support the N&P content remark, which seems to me so self-evident that I would not know where to look for a citation (I was not the author btw, just passing). Surely a comment equivalent to saying that blackwater contains more muck than greywater doesn't need citation, any more than the claim that water in drains runs downhill needs one??? JonRichfield (talk) 07:02, 4 September 2012 (UTC)

I'm just driving by this talk page - haven't looked at the content you're referring to, but there must be tables of breakdown times for different waste streams under various treatments. Jojalozzo 16:11, 12 September 2012 (UTC)

Well, that is OK as far as it goes, but this is not a quantitative claim; if someone had said "Greywater typically breaks down 3-5 times faster than blackwater depending on oxygenation and temperature and has levels of nitrogen and phosphorus 5-7 times lower." Then citations certainly would be needed (a lot of them, given the vagueness of the claim!) But as a non-quantitative though relevant remark, the text seems pretty unobjectionable as it stands. JonRichfield (talk) 18:33, 12 September 2012 (UTC)

Complete Overhaul[edit]

I am planning on overhauling this page over the next month or so, one section at a time, I am an expert in the field and the page, as it currently stands is pretty conflicting with professional opinion, British and International Standards, I will be bringing the page in-line with BS8525 : 2010 part 1 and 2 and also with references to the american LEED standards. The combination of these two standards should bring the whole page up to date with most current international views of grey water and it's use in recycling.

Please use this "talk" section to comment and help me bring this page up to scratch, I will be using comprehensive citations to the relevant sections of each standards, however I am based in the UK with experience of UK, US and Middle East markets and standards. I would greatly appreciate input from other geographical areas. Will Douglas Shearer (talk) 21:08, 26 June 2013 (UTC)

Image Change[edit]

I have changed the image to a real grey water recycling system - myself and many other people have all commented on how silly the image of a wash hand basin sitting atop a WC cistern is, it really bares no resemblance to what grey water recycling is about. I have added a small domestic system with no branding, please feel free to comment, perhaps we could add another image of a larger commercial MBR or Multi-media filtration system too.

Thanks Will Douglas Shearer (talk) 21:33, 26 June 2013 (UTC)

non sequitur[edit]

"Sewage can then be treated to limit pollution and health risks" "Then" should follow one of two things. Either a previous step in the process, or a conditional "if" statement. Which is this supposed to be? (talk) 11:14, 15 December 2014 (UTC)