Grey Water Reuse: Safe or Not?

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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?

 

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56 Answers

  1. Dear Researchers.

    For water use on duty such as kitchen wash, bathing, regular laundry, others- it is apt to use organic soaps and cleaners.

    In the effluent from these uses, at best have basic treatment in septic tanks with stones. boulders and plants Etc.

    Then this wwt water can be used for seconday uses. 

    Well wishes .

    Pro. Ajit Seshadri Chennai. 

  3. The speaker who was opposed to reuse had no idea what she was talking about. Water can be reused for any application with appropriate treatment and finished quality. The treatment and quality specifications are determined by the end use and human contact potential. The World Health Organization released guidelines for direct and indirect potable reuse. You can find them on line at www.who.int/water reuse. There are numerous large scale reuse projects in operation and many more being planned.

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  6. Many health jurisdictions in North America permit single-family residences to recycle ( i.e. without treatment) greywater  (typically defined as bath/shower, lavatory and laundry drainage) for direct shallow (within the root zone) subsurface irrigation.  There are two Canadian municipalities that  allow recycled greywater to be used for toilet flushing without treatment by capturing bath/shower water and pumping it to the toilet as required.  These are "smart" systems that drain the stored greywater to sewer if the storage time exceeds 24 hours, automatically top up the water in storage with potable water (if  required), and have UPS power supplies in the event of a power failure.  This simple practice could save up to 30% of a household potable water demands and reduce the volume of wastewater generated by the same amount without the burden of treatment costs.  The principal impact on the household is a  more frequent need to clean biofilm from the toilet tank and bowl.  The expressed concerns I have heard are primarily related to the potential for disease transmission as a result of a person coming into contact with droplets of water as a result of flushing.  However, common sense dictates that fecal deposition and bowl contamination from previous users of the toilet are a significantly greater health risk -one that we accept, particularly with respect to public toilets.  Further, intuitively, we can appreciate there is a much greater risk of disease transmission within a family as a result of interpersonal contact and food preparation, that there is with incidental potential contact with bath water used to flush a toilet.but 

    Here is a link to the ConservePump greywater recycling system that was manufactured by iDUS Controls designed to recycle bath/shower drainage for toilet flushing.  I am not sure the company still actively markets the technology, but the link provides information on how the system functioned.  It was installed in homes in Nanaimo, British Columbia, and Guelph, Ontario, Canada.

    http://www.waterwisetech.net/specs/idus_conservepump_home_product_data_sheet.pdf

    An International Association of Plumbing and Mechanical Officials (IAPMO) committee developed a small-scale residential greywater recycling performance Standard 1207, in 2014, that failed to receive approval because of unfounded concerns the practice posed a health risk.

    The Sloan AQUS system also directly recycles greywater from lavatories for toilet flushing without treatment, but does incorporate a simple chlorine puck system for disinfection.

    https://inhabitat.com/sloans-innovative-aqus-grey-water-toilet-system-makes-every-drop-count/

     

     

        

    1 Comment

  7. The surfactants and synthetic chemicals would have a negative impact on the environment. Especially in our rivers and oceans. Please visit http://www.goesfoundation.com/ to see why. This is why I do not recommend reusing grey water without treatment. 

    Modern pharmaceuticals and other chemicals are becoming increasingly harder to breakdown. The government here considered this a few years ago. I would recommend otherwise until we learn how to treat these new chemicals. 

    Hydrodynamic cavitation could be the key, we have successfully removed 91 agricultural chemicals for a drinking water project here in Australia recently.

    A membrane bio-reactor could be used although, the bacteria may not survive if concentrations of synthetic chemicals are too high. We have had a successful reuse project in China using this method of treatment for a hotel. The treated effluent is resued for their toilets and wash basins.

    1 Comment

    1. The Goes issues are generally irrelevant to recycled greywater. Recycling actually reduces transport to waterways and oceans, Soil applications allow soil bacteria to degrade many chemicals, about as well as sewage treatment plants. Recent pharmaceuticals are not more or less degradable then older ones. The most relevant question is whether certain substances would be taken up by food plants. Of course, waste recycling has been used for perhaps thousands of years, but it is probably better to avoid use on food plants, primarily because of  possible pathogen recycling, if the wastewater or night soil has not been composted or sterilized. There are standards for that.

  8. Yes, we need to reuse water, we often CAN get away with it. However, our ignorance is still very great, risks abound, and we always need to reduce our ignorance. Fortunately, ignorance can be fixed.... with enough new knowledge to gradually identify and reduce the harm. On the other hand, you can't fix "stupid' as easily. Science is the key, and is always increasing, always needed, and is essentially never done. We, far too often, assume 'safety' when we are short-cutting the science. When we take scientific shortcuts, we always need to acknowledge our ignorance, try to decrease it, and fear our hidden stupidity. 

  9. This is a complicated subject, and there have been some very good comments, reuses a huge need in many geographic areas. We have created about eighty-five thousand chemicals mostly new to the environment, to put into products we have been using, these products are dispersed around the world to eventually degrade often becoming pollution. Very few have had adequate toxicity testing done. Water is a solvent and transporter of most of these chemicals. Grey water is contaminated by a huge number of these chemicals, but highly variably. We have not even developed test protocols for identifying multiple thousands of these contaminants. Extremely low doses of many chemicals can have adverse biologic, and pathogenic, effects that we are unaware of of even having, let alone ascribing causation to. Some of these chemicals are accumulative in our bodies. They can be additive in adverse effects, and even synergistic in subtle-but-persistent low dose effects as mixtures. Science is able to look at many toxic effects of many of these chemicals, but does not do a very good job of identifying toxic effects of mixtures of them. There are huge gaps in our knowledge of the toxicologic effects potentials and our ability to tease out the risks in grey water that is highly variable. Anything we can do to gain additional knowledge about these very real health risks is going to become even more essential as clean freshwater becomes increasingly contaminated by our products. The science is critical, we are harming ourselves and others, but often it is very subtle to determine adequately.... we are not very good at this yet... but we must keep getting better at it rapidly IMHO

    1 Comment

  10. There has been so many mix reviews regarding the topic at hand and I thank each and everyone for your participation. There are no clear yes or no's BUT what I gather from all the replies is that:

    Yes, you can re-use gray water but Pre-treatment is IMPORTANT and Direct re-use is not advised.

    1 Comment

    1. Hello I do not know which sources come from the yes for the reuse of greywater. Ray Kinney's post should still enlighten you on the subject. Reusing greywater is a crime against humanity. No one can assure that these grey waters do not contain very toxic products. As the only treatment to date of greywater is of the order of filtration, no device is able to eliminate dissolved pollution.  
      Everything alive on our planet feeds on organic. is a water impregnated with undetermined chemical molecules biological?

  12. Definitely safe, but it takes bread out of mouths of water treatment companies and EP agencies.
    IMHO

  13. Hello Ghoewylah,

    As grey water does not contain poop, urine, and too much contaminants, it can directly be used for watering gardens and other landscape uses. But, I'm really not sure if grey water poses threat to human health when using for flushing toilets. 

    1 Comment

  14. As you know there are at least 50 shades of grey!

    We go for the lightest one, starting by (retrofit) upgrading the upstream biological treatment as to achieve ultralow residuals. This enables the highest water quality after UF + NF/RO as demonstrated at full scale in a sewage to drinking water project via ground water recharge under strict HACCP. The quality of the drinking water at the tap and its taste improved significantly in all parameters since this was project was completed in 2006.

    Regards, Bruno

  15. In the 1970's I lived in Livermore, California, which is somewhat arid.  As is often the case, there was a drought and water use was being restricted; could not water the grass or wash your car.

    I set up a gray water system for my lawn and garden and used it for several months.  Since my lawn was very green, I had the pleasure of a government water company official pay me a visit accusing me of violating the restrictions.  I showed her my system which didn't impress her.  She stated that the wastewater facility depended on the gray water to dilute the black water solids and that I needed to stop my reuse.

    I did stop watering the lawn, but did keep using it in my garden.

    I have no such reuse needs here in Pennsylvania.

    1 Comment

  16. I wouldn't advise using the grey water untreated like previous comments, however, there are good filtration systems. Not to turn this into a sales pitch but we have a system developed utilising organic filters that treat most of the nasties. This is in progress with United Nations and UNICEF currently.

     

    I would be more than happy to have further dialogue with you. Let me know if you this would be of interest. Thanks in advance.

  17. Using grey water to grow crops in constructed wetlands  placed  and planted sequentially may be an answer. Prairie grasses are excellent phytoremediators of heavy metals and can be used for gasification to produce energy while capturing the metals. A series of 5-6 sealed constructed wetland bays  with gravity flow following the grasses that are planted with crops matching declining nutrient needs and increasing salt tolerance (EC) may completely remediate pathogens on root surfaces, consume most of the effluent, prevent groundwater contamination, and prevent alkali soil conditions. Remaining phyto-treated water could be used for groundwater recharge. Edible portion of crops would not contact pathogen contaminated water, no aerosols would be generated, and CEC's would be remediated by energy crops. 

    Water-Energy-Food--solution for one is the solution for all.

  18. Answers below address issues of pathogenic aerosol from application methods, pathogenic contamination of edible portions of crops, and plant uptake of solubilized heavy metals--all of concern. One must also note that alkali conditions can damage soils in dry climates--most grey water contains high levels of salts , and over application can contaminate ground water sources--NO3-. 

    However, grey water is a great source of irrigation water for many reasons: contains nutrients, source of water in drought, use reduces eutrophication of receiving waters...

    Aeration helps to reduce pathogens, subsurface irrigation reduces chances of contaminating edible portion of plants (changing water sources 15 days prior to harvest is common), and source testing can identify heavy metal polluters. (e.g.  itai itai).

    Hydroponic methodology can eliminate damaging soils with alkalinity or heavy watering during seasonal wet periods.

    More care in using fresh water will reduce the issues encountered by recyclers.

    Water-Energy-Food, the solution is obvious, reusing water.

  19. Here in California we have very strict greywater reuse stands where all of it has to be treated for biological contaminants and other constituents of concern including heavy metals, suspended solids, etc. before final end use which at this time is only for non-potable non-crop landscape irrigation. There isn't sufficient studies and data as of yet showing that it's safe to reuse for potable water reuse. In my job as an Environmental Engineer we've only had a couple of greywater treatment system applications for landscape irrigation reuse and even with that the reporting requirements are very strict due to potential for public exposure with the sprinkler system spray. So it really depends on a project by project basis for feasibility of greywater treatment for reuse but 99.9% it has shown to be safe for non- potable landscape irrigation reuse when treated properly.

  22. Many commenters are expressing a lot of unfounded angst, mainly from their inexperience. Actually grey water and other water reuse have been practiced for many years safely. Wastewater is 100% recyclable. Quality standards and appropriate treatment based upon end use are well established. We are not running out of water. We are running out of free or wasted or cheap water in some locations where population demands are overtaxing local natural supplies. Of course, the first principle is to reduce wasteful use.  Apart from conservation, which has limits, proper reuse of all types, including potable reuse, is the best opportunity for quantity, reliability and sustainability. The experienced and creative engineers, not the amateurs,  know how to do it.  The public needs to be informed with facts so they can support the recycling efforts. WHO has new direct and indirect potable Reuse  Guidelines coming out this summer. It already has published other water use guidelines.

    1 Comment

  23. See below, the treatment you just mentioned in not correct, you have to remove all the  contaminant disinfect the water and then use for flushing

  24. Reuse using subsurface drip irrigation for anything except root crops is 99.99% safe.

    1 Comment

    1. Does salt increase in those soils often, but slowly? Do pharmaceuticals, or any other potentially toxic chemicals accumulate in some of these soils? Do drip holes gradually plug with deposits?

  26. Grey without treatment can pose health risk.

    With regard to grading e.g. flowers, it could be used in restricted area (fenced area) where no access allowed. However you have to bear in your mind that by time the concentration of detergents and other elements will have a detrimental impact on soil and plant's growth. 

    For toilet flushing you need at least residual chorine -0.5 to 1mg/l to ensure some safety. The danger of not treating and disinfection grey water, by time, will encourage growth in the e.g. toilet tank and toilet tank will be an incubator to microbiological pathogens. 

    In some country using unauthorized grey water is illegal.

    Should you required further clarification, please do not hesitate to contact me.

    Regards,

    Majed Murad, BSc, MSc, CEng, C.WEM, FCIWEM, CEnv.

    Email: majedmurad@hotmail.com

     

     

     

    1 Comment

  27. The toxicology potentials are NOT even known well, because we can not even know effectively just what toxicant actually exist in a given grey water. If you can't really know WHAT to test for in a sample, and many toxicants do NOT even have analytical protocols developed, how can we in good faith due diligence scientific integrity state whether or not a reuse is 'safe'. There will always be reasonable doubt about the safety. 'Safety', is always relative, but we have existential responsibility to use all available caution in public health best management practices. Clean, freshwater scarcity is an immense pressure to shortcut the whole investigatory aspect of due diligence assessment, this is a very important issue. To be more a part of the solution than a continuing part of the problem for public health responsibility, we must all 'doubt, without unbelief, of the  things to be believed'. We have great responsibility, and tools that are not yet adequate to use, but must always strive for excellence, while fearing we are not really being adequate. Short of reverse osmosis everywhere, we must strive for diligence. IMHO

     

  28. we , at huliot in israel manufacture the ClearGrey grey water plants , for the last 5 years . withe 2 kind of systems SBR type , with a secondery efluent qualty . and MBR type system for a tertiary efluent qualty . 

    1 Comment

  29. My suggestion is to have your Garden as Vertical Wetland, simple easy Wetland will give a proper look of a Garden too. Instead of going to complicated solutions, Vertical Wetlands are the cheapest and easiest solution for such areas where houses have Gardens/Lawns or ample land available.

    On the other hands, if you filter the grey water and disinfect (with Chlorine the cheapest disinfectant) and use it for Flushing the Toilets could be a solution. 

  30. The grey water can't reuse to any purposes by without pre-treatment. Please see more  information on WHO standard.

    2 Comments

  31. Quality of grey water depends on the use of water. In areas of low-income people, where water availability is low, and use of water itself is low, the grey water becomes highly concentrated in terms of its impurities. One might think twice before using such grey water.

    On the other hand, in areas of high-income people, where water availability is high, and the use of water is lavish, the grey water is diluted and can be reused.

    F H Mughal

    Karachi, Pakistan

     

  32. Grey water is most commonly used as an irrigation water source, however, if not suitably treated, this source can contain pollutants (e.g. Heavy metals) that actually cause long-term destruction of the soil fertility

  34. Reuse of Grey water depends upon. BOD .COD etc. hair,impirities. The hair can be removed with simple strainer. Some treatment is required for reuse like sand filtrationetc.

    The relatively clean waste water from baths, sinks, washing machines, and other kitchen appliances.Grey water can be defined as any domestic wastewater produced, excluding sewage. The main difference between grey water and sewage (or black water) is the organic loading. Sewage has a much larger, With proper  treatment grey water  can be put to good use. These uses include  water  for laundry and toilet flushing, and also irrigation of plants.  Treated grey water  can be used to irrigate both food and non food producing plants.

    The grey water cannot be used in vegetable garden,if you want to water herbs and vegetables you'll need to get a higher level of water treatment. Untreated grey water should definitely not be used on food that will be eaten raw.

    Untreated grey water should only be used for sub-surface garden irrigation — that is, through a network of pipes buried at least 1m below the ground – to reduce the risk of human or animal contact.

    Following instruction may be follows-

    1. Pipes carrying untreated grey water must display relevant warning labels.
    2. You can't store untreated grey water, because the bacteria and other pathogens could multiply to dangerous levels.
    3. Use it immediately (or within 24 hours), and if it's raining, divert it to the sewer.
    4. If someone in your family is sick with gastro or flu or another contagious disease, stop using the grey water.
    5. Don't use grey water if you've been washing  nappies  or using bleaches or dyes.
    6. Don't water herbs, vegetables or pot plants with untreated grey water.
    7. Your grey water shouldn't escape from your property into a neighboring one, into storm water systems or aquifers used for drinking water — in fact it's illegal.
    8. Small amounts of phosphorus can be useful for plants, and it's a major component of fertilizer. When it gets into waterways, however, it can cause excessive algal growth, leading to toxic algal blooms. The effect on your soil is varied depending on your soil type. Clay soils can deal with more phosphorus because the phosphorus binds to clay minerals and doesn't leach away. On sandy soils, excess phosphorus can leach into groundwater. Australian soils are typically low in phosphorus, and some native species can't tolerate high levels.
    9. All laundry detergents contain salts, typically sodium salts such as sodium nitrate, sodium sulphate, sodium phosphate and sodium silicate. All laundry detergents are highly saline, and frequent long-term use would likely harm your garden, unless it was spread over a large area.

    1 Comment

  35. Also http://www.nexusewater.com/ has systems for household filtration and reuse of greywater, including heat recapture.

    1 Comment

    1. French English

      Bonjour 

      Voilà comment des gens induisent le monde dans l'erreur: dire que untel ou un autre installent des filtres domestiques et recyclent les eaux grises.

      Bien sur, tout le monde est capable de faire du grand n'importe quoi surtout si cela plait comme information utopique.

      la filtration retient la matière en suspension: un dispositif qui colmate au fur et à mesure que l'on s'en sert. A quel moment n'est-il plus efficace?

      la pollution dissoute dans le liquide passe à travers le filtre . Une pollution dissoute que l'on retrouve tôt ou tard dans notre environnement

      Je ne vois nul part une quelconque notion d'épuration. Hors les eaux grises contiennent beaucoup de lessiviels. Que devient cette pollution? 

       

      Hello this is how people lead the world in error: say that so-and-so or another install domestic filters and recycle greywater.

      Of course, everyone is able to make the great anything especially if it pleases as utopian information.

      the filter holds the suspended matter: a device that seals as it is used. When is it more effective?

      pollution dissolved in the liquid passes through the filter. Dissolved pollution found sooner or later in our environment

      I don't see anywhere a any notion of purification. Out of the grey water contain a lot of detergent. What happens to this pollution?

  37. Dear

    Gray water still contain BOD less or equal 80 mg/l so you need at list filtration and disinfection,  if you need more information send me.

  38. Health and Safety requirement for using Grey Water: Grey water may contain organisms that are found in black water and may transfer diseases to human beings and present health risk. To avoid these conditions, the following requirements should be taken into consideration:

    1. Designing appropriate greywater system according to the estimation of greywater from each household.

    2. Greywater should not be stored before or after treatment more than 24 hours.

    3. Greywater system must be maintained and operated by a well trained person.

    4. Fresh water should be used from time to time to minimize build up of negative effects on soil properties and drip irrigation system.

    5. Spray irrigation is prohibited.

    6. Avoid direct contact with greywater.

    7. Avoid inhalation of spray coming from greywater.

    8. Do not use greywater for washing or bathing.

    9. It is not allowed to discharge greywater through storm drainage network.

    10. The greywater system should be operated and maintained in a well programmed manner.

    11. Do not construct the greywater pipes near drinking water pipes to avoid cross contamination.

    12. Greywater should not be used in a manner that may result in a direct contact with vegetables or plants eaten raw.

    13. Greywater should be used on the site where it is generated household (property boundary).

    14. It is advisable to construct the irrigation pipes below the soil to minimize odor problems coming from the greywater.

    15. Avoid using greywater if there is a family member with an infectious health conditions.

    16. Avoid using greywater discharged or mixed with washing diapers.

    17. Avoid using hazardous chemicals in washing activities discharged to greywater system.

    18. Avoid making pools resulting from greywater reuse activities.

    19. The property area to be irrigated should be suitable to the generated greywater quantity on a daily basis.

    1 Comment

    1. French english

      Bonjour 

      il y a quelques années un sujet de traitement des eaux grises et d'un recyclage éventuel aurait eu des déclarations assassines. 

      aujourd'hui peut de gens comme vous soulève la problématique de la pollution dissoute.

      Mais ce qui est grave ce sont ces gens qui lancent des sujets comme celui ci pour être dans le moment, pour se faire bien voir.

      Recycler des eaux usées sans épuration est un crime contre l'humanité 

      La vocation d'un filtre est une fonction séparatrice.

       

      Hello a few years a subject of treatment of grey water and eventual recycling would have been murdered declarations. 

      today can people as you raise the issue of the dissolved pollution.

      But which is serious, what are those people who start topics like this one to be in the moment, to ingratiate himself.

      Recycle wastewater without treatment is a crime against humanity the vocation of a filter is a separator function.

  39. Simple steps to reduce the BoD by anaerobic digestion of organic solids reduces the risks of using partially treated grey water for irrigation. Any way, in developing nations, grey water is getting used for irrigation even though we call them rivers sources !

    1 Comment

    1. Anaerobic digestion has neither be simple, nor safe to reduce risks of bacterial contamination. In fact it could provide quite opposite.

  40. Query by GDarries on re use of grey water. If the treatment has remediatoin done by plants in its later stages then these davrificial plants will reduce the BOD levels. A bit of sun exposure takes care of curing and UV rays to part sterilise the treated water. When this water is used for plants then the veggies grown to be consumed with caution...st best deep fry them avoid eating thrm raw or in boiled form... w wshs ...

    Prof.Ajit Seshadri.

    Vels University.Chennai. 

  41. 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. 

    1 Comment

    1. 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?

  42. 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.

  43. 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 !!!

    1 Comment

    1. 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?

  45. French english

    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.

    1 Comment

  47. 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.

     

     

  48. Dear Ghoewylah,

    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...

  50. 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.  

    2 Comments

    1.  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.

    2. Thanks Guy! Could you provide link(s) to what I can read to get more from your comment?

       

      1 Comment reply

      1. 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

  51. 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.

    1 Comment

  52. 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.

  53. 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. 

  54. 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.  

    1 Comment

    1. 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

  56. 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.

    1 Comment

    1. 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