I recently attended a reuse symposium, where reuse of various types of water were discussed.
One speaker spoke of how wrong and absolutely risky it is to reuse grey water if not treated before reuse. She was emphasizing the extreme health risk it poses for direct reuse.
A following speaker spoke of how they directly reuse grey water to water gardens and flush toilets in a community project. This speaker said that there are no serious health risks to this application.
We in South Africa are experiencing a serious drought. South Africans are reusing shower/bath water to water gardens or flush toilets in our area.
So my question is - is it safe to reuse grey water for gardening and flushing toilets without treating? What health issues could using grey water in gardens pose? Is there anyone who can shed light on where we can we use grey water without pretreatment?
I would say it is safe to use in the toilet (why use freshwater for that?) but for gardens it's trickier, and safety depends on what is in the grey water (what was it used for?) and what you are growing (what will it be used for?).
For instance it may be safe to use on trees or a lawn, but not safe for vegetables that you eat raw (particularly if it contains animal wastes of any kind, even from dish-washing). Also, if it contains a lot of soaps you can cause problems with too much phosphate in water and soil leading to eutrophication or enrichment. Or, it may contain more toxic cleaning products or even fragrances and surfactants , that may be harmful to ingest from food crops, or harmful to soil microorganisms that you rely on for a healthy garden.
It isn't a 'yes' or 'no' answer, but water conservation is always a good thing. I would use it to flush, and use things like the water used to cook vegetables, grains, etc. be used for the garden (as long as there is no salt in the water) as it is full of good nutrients, with nothing harmful.
Hi Judi, I agree that water conservation is a good thing, and that use of grey water can often have more benefit than risk, but there always remains an unknown amount of risk in grey water use. Funding for 'best available science' in resultant water quality sampling and toxicologic analysis is always short changed..... and degrees of risk remain. How much risk are we willing for our own two year old child to be exposed to in any given grey water use scenario, and how sure are we that we are not harming that child?
In the arid SW of the USA we have been using grey water to irrigate golf courses, parks, crops and gardens. I can't speak to reuse for the home interior but reuse of grey water has been studied quite extensively in the US. You might want to query the Department of Agriculture for some of the research that has been conducted on this topic. Much of the DOA work was in conjunction with EPA. As noted Constructed Wetlands have the ability to remove most contaminants except some pathogens. We use wetlands to remove heavy metals and have been doing so for 30 years. www.rmc-ut.com.
Grey Water will be the forthcoming global generation's water banking enterprise. Fresh potable water is rapidly becoming the highest priced and sought after global commodity - WE ARE RUNNING OUT OF USABLE QUALITY WATER !!! Grey Water should be used for all secondary water uses; however; untreated grey water exponentially raises the "risk factor" pursuant to intended application. My humble advisement is that -"it is better to be safe than sorry" ! All used water should be treated at the tertiary level for production of Gray Water !!! Without careful chemical characterization of the constituency and concentrations in the target "Grey Water"; using the recycled water; untreated; could prove highly risky, even for gardens, etc. ! In today's polluted planet situation; we never know exactly what is in our water without decisive analytical screening; any other use protocol would be a great "gamble" with Public Health, Welfare, Safety, and the Environment; even for agricultural purpose. We do not now live in the same planetary state as when water was "safe" to readily use untested; we have collectively compromised our global water quality and must carefully analyze every drop before use. Hopefully; in the not too distant future we may restore our planet's air, earth, and water to health !!!
Good points, use of all grey water systems increases risks. We do not know what all of the pollutants ARE in a given grey water, so how can we be sure we have adequately cleaned the water for appropriate use. Extensive experimental sampling, analysis, and assessment of toxicologic risk is essential, yet would still likely not recognize/remove all toxicants. Utmost testing, with scientific integrity, will be essential, and that is a tall order since it would probably be prohibitively expensive. We have created more than 85K largely new chemicals with which to contaminate water with by our uses, many of these have toxic effects, especially at chronic low dose accumulative levels that can be minute.We DO NOT, historically, do sufficient pollution assessment due to cost and difficulty of analysis.
Not testing adequately is risky, currently not even possible, and funding to try to do due diligent science always gets short-changed. So, it comes down to 'best management practices' which are NOT best available practices at the scientific level. It seems like we should keep in mind: how much risk to our two year old child are we willing to risk for any given use of grey water?
Bonjour Je suis le seul au monde à pratiquer l’épuration -biologique- des eaux usées.
Il ne suffit pas de dire: faire du traitement biologique pour qu’il y est un traitement biologique, car il n’y aura aucun traitement.
Je supprime de mon vocabulaire le mot traitement puisque justement il n’y a pas de traitement et je le remplace par le mot EPURATION.
Pour faire de l’épuration -biologique- il faut certains paramètres -biologique - dans des conditions -biologique-.
Sinon ce n’est rien du tout, que du cinéma. C’est d’ailleurs pour cette raison que l’assainissement en général produit autant de résidus boueux.
Plus de 45 millions de tonnes de résidus de boue, quand avec mon procédé -biologique- j’élimine la totalité des excréments.
Bien sur que non il ne faut pas tenter de recyclage des eaux grises pour quelques projets que ce soit.
Les eaux grises contiennent des pollutions qui non épurées vont contaminer l’environnement. Si en plus cette pollution est constante le lieu de réception va vite saturer et sera contaminé pour des années.
Idem pour le nettoyage des toilettes. Les toilettes, lieu de défécation sont l’endroit le plus -biologique- de nos habitations. Hormis les cas spécifiques et ils sont nombreux ou les gens nettoient avec de l’eau de javel.C’est l’endroit le plus -biologique- de l’habitat car nos excréments sont totalement -biologique- et que lorsque nous tirons la chasse d’eau pour évacuer nos excréments l’eau vient des canalisations d’eau potable donc -biologique-
Rincer avec de l’eau polluée augmenterait le rejet d’eau polluée dans l’environnement et détruirait les caractéristiques -biologique- des excréments.
D’un point de vue -biologique - je déconseille totalement cette idée
Hello
I'm the only one in the world to practice the - biological - treatment of wastewater.
It is not enough to say: making biological treatment so that there is a biological treatment, because there is no treatment.
I delete my vocabulary the word treatment since there is precisely no treatment and I replace it with the word treatment.
Treatment - biological - to some - biological - parameters in conditions - biological-.
Otherwise it's nothing, than to the cinema. It is for this reason that sanitation in general producing so much muddy residue.
More than 45 million tonnes of residue of mud, when with my - biological - process I eliminates all of the excrement.
Of course not do not try recycling gray water for some projects either.
I'm the only one in the world to practice the - biological - treatment of wastewater.
It is not enough to say: making biological treatment so that there is a biological treatment, because there is no treatment.
I delete my vocabulary the word treatment since there is precisely no treatment and I replace it with the word treatment.
Treatment - biological - to some - biological - parameters in conditions - biological-.
Otherwise it's nothing, than to the cinema. It is for this reason that sanitation in general producing so much muddy residue.
More than 45 million tonnes of residue of mud, when with my - biological - process I eliminates all of the excrement.
Of course not do not try recycling gray water for some projects either.
it is safe to use grey water for drinking it after treatment with ozone-in fact such solar powered gadgets are available in india @ 90 each for home use
I agree 100% with Chetan Shukla. Grey water without any treatment is great for watering. Before it can be used to flush toilets, it must be filtered. Can use the grey water now for watering until the best treatment is determined for flushing toilets.
It is obvious that many people have different opinions on this matter. My company designs and builds constructed wetlands for more than two decades now. And we have projects in many countries, many climates. Usually the domestic projects mean: treating both grey and black water. We do want to keep those streams separated for the pretreatment, after that we bring them together to direct it into the constructed wetland.
We have many projects where the final effluent is being reused. Not for drinking purposes, I consider that too risky. But for toilet flushing and irrigation or for discharge in a pool. We face no difficulties with that, If the effluent is not reused it can be discharged directly in the environment, it meets the (Dutch) regulations.
Chlorination is something we NEVER do, that is a technique from the past. Our reuse is based on exclusively natural processes and that is enough NOT to worry about pathogens and heavy metals. There is a lot of knowledge among the people who are involved in constructed wetlands (scientists and engineers) and there are countless reports and analyses to support what I just wrote...
Depends on what you call pretreating. Allowing nature's microbes to biodegrade grey and black water in an enclosed setting may be considered pretreatment. But usually people think CHLORINE is a pretreat item. When using the Archaea group of microbes all organic compounds are reduced to their elemental/nutritional form. It eliminate odor, will not allow methane production, and chelates any and all toxins into their non toxic state. This way the water will be potable and ready for reuse in your water storage home system. (in addition a biogenerator can be connected to the biodigesters to collect loose electrons to make electricity for your residential needs. Catch rain water, install water cistern , make a home garden, green house, food storage program. Drought passes you by, food quality and quantity increases, zero waste, and allows you to work towards being 100% off the grid and 100% sustainable.
This is septic tank water 24 hours after being "treated" with the Archaea RNA microbes. Test lab reports: no pathogens found, oxygen content 3x . Potable, super oxygenated, and trace elements in their elemental/nutritional form.
Please use my personal email and I will send you pictures (biozomesales@biozome.com) reports and testimonials. Many things to discuss. This is the highest form of cutting edge technology on the planet. If you skype you may use mine to chat etc. I can talk faster than I type. skype: guy_mcgowen
I might add that grey water reuse is generally driven by water scarcity and, as you have mentioned, this is becoming a serious issue in South Africa. Prof. Anthony Turton has written extensively on the subject and speaks his (expert) mind rather than adhering to political agendas. I recommend reading some of his papers.
Grey water is already a necessity in parts of SA, and black water recycling for direct potable water use is likely to be implemented soon as has been done in Windhoek and in Singapore for several years. This does, of course, require substantial (and expensive) treatment, but when scarcity becomes critical then economics don't matter.
Pulling together some of the things said already, grey water from baths, showers, sinks etc. is generally safe for garden watering (as long as you're not going to consume fruit/veg shortly after watering) and for flushing toilets. There are a couple of points to note:
The organic residuals in grey water mean that the toilet and cistern are liable to get dirty over time.
The recycled water pipes need to be clearly marked to ensure nobody connects into the pipes for other purposes (such as to add a potable water tap!)
Filtration may be useful to prevent fibres or small solids blocking the fittings / spray heads.
Disinfection of greywater for these purposes is not usually necessary. Any pathogens in greywater are going to be present in your soil, and if you're flushing your toilet with it then any aerosol generated during flushing is liable to contain traces of pathogens anyway. There's a small risk if spraying grey water onto the garden, but fairly minor.
Recycling automatic washing machine water for these uses is generally NOT recommended because the detergent is much more concentrated and it should be treated as black water instead.
The answers you have received here are not reflecting the entire aspect of grey water. If you are using only grey water, i.e. water from bathing, washing, and from clothes washer then it is perfectly safe.
Presence of phosphates in the grey water are an ideal source for the plants. Additionally the bacteria in the soil assist in breakdown of the wastewater and uptake of the nutrients to the plants.
It is very clear that the grey water should have no presence of black water, as black water is full of pathogens. Black water is used in several parts of the world as irrigation water but there are 2 fears, firstly presence of heavy metals in the black water and the other is presence of pathogens. Both of these need to be removed before using for gardening.
Flushing toilets is one thing. I'm sure it will require you to clean toilets more often. For the garden, I would ask what kind of garden? I would not use it for anything you plan to eat.
I was actually ask it in general. To answer your question, people use it to water their grass and keep the lawn green. However, kids do play on the grass, so the question would be, do you put this under the same bracket as Treated wastewater effluent.
To elaborate on this: Treated effluent from WWTW (After disinfection) is used by surrounding areas to keep the grass nice. However, we have rules to say that non-contact sports should be played on the grass. So do we put this rule to untreated grey water when using it for the lawn. Here grey water will include shower, baths, sinks and washing machines
Dear Gloewylah, I strongly recommend against the uses of grey water, if not treated properly. It could be very unsafe. The treatment is not necessarily complex. It could be a simple biological treatment.
I do understand that ruling of the appropriateness for directly using grey water depends on the sources contributing (baths, sinks etc.).
May I ask what is your main concern for direct use of bath/shower water on the lawn and flushing toilets? Keeping in mind that toilets will have to be cleaned more frequently should reuse take place