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Greywater re-use & purification: Bangalore, Whitefield

We are building a 4-bed, 4-bath house on a 60'x40' plot in Bangalore, Whitefield area. Although there is a sewage network in the area, we wish to recycle the grey water from shower/washbasin/laundry.

  • What kind of filter tank is required? Do you have any diagram?
  • Do you require root zone treatment or any aerobic treatment?
  • Can this grey water be used for flushing?
  • Can this grey water be also used for drip irrigation?

Based on past questions, i understand that it requires aeration & coagulant. However, there was no info on area or volume requirements. Since this is just a 60'x40' plot with probably available green space of 10'x20', I was wondering if this kind of treatment is feasible?





Dear Mr Kumaresh.s,

Please go on to the websites below they have the information you require...

Hope you get all the answers here..
all the best..

Dr. Anil Lalwani


Dear Kumaresh.S,

The area available in question is acceptable. However, please be reminded that root zone treatment or any other non-mechanised treatment is natural and generates a little smell, some mosquitoes (in our type of climate), is non-asthetic (owing to a layer of algae on top) and is generally not very pleasant for a residential area.

The treatment efficiency of such a plant is not very high and as such, would not be a good idea to use it for the application desired. The very reason mechanised treatment has been in use is because of the above mentioned inherent lacunae in process.

With best regards,

Taral Kumar
Executive Director
Akar Impex Pvt. Ltd.
Noida, Uttar Pradesh


Dear Kumaresh.S,

Approximately 60-70 % of the used water in a household is grey water and if you exclude the grey water coming from Kitchen and washing machine then it would be sufficient to flush the toilet.

In this case no treatment is required for the grey water coming from bathing and shower area and can be used for flushing. You need to have separate pipes for black and grey water from toilet and collect it in a tank through a rough filter for stopping hair etc and then pump it to roof tank connected to cisterns in the toilet. The space requirement would be very minimal and it is based on the assumption that no treatment is necessary for grey water when it is used for flushing.

In case if you want to recycle the grey water coming from Kitchen and laundry also then you need to have a system which requires space fro grease trap, three compartment filter tank/ sand filter etc. and after that treated grey water can be safely used in irrigation/flushing.

There are many simple schematic arrangements in which you can recycle the grey water but for small urban plot where space is constraint it is preferable to recycle grey water for flushing.

With regards,

Prakash Kumar
Ecosan Consultant
EcoSanRes Program
Stockholm Environment Institute


Dear Mr. Kumaresh,

Let me congratulate you for planning to recycle the waste water from your house.

Answers to your questions are as given below.

Answer - 1 Use of simple tank will not serve the purpose. We recommend to segregate the sullage (gray water from bathroom and kitchen), & sewage from WC. WC can go to the septic tank followed by soak pit. Gray water can be treated and use reuse.

Answer – 2 Aerobic treatment for individual house is not economical. We strongly recommend to use Root zone cleaning system. We are working on this system for last 10 years. We have supplied many plants for farm houses end small residential complexes. On every day we reuse 40 l of treated kitchen wash water from Root zone cleaning system. A photograph of the Pilot Plant and the plant in field is given below.

Answer – 3 The gray water cannot be use directly for flushing. However treated gray water can be used for flushing and irrigation.

Answer – 4 No it will chock the drips due to suspended solids in gray water.

If you need any further information then please call us or do write to us.

Prof. R. V Saraf, FIE, FIWWA
Viraj Envirozing India Pvt. Ltd.
21, Radhakrishna, Near SBI Paud Road Pune 38. India

TEL: 020-25433445 FAX: 020-25433445
Mobile:+91 9822186763
Website :


Dear Kumaresh,

You can use the terrace for treatment facility.Collect all the grey water in a tank at the lower level and pump the same to a root zone treatment system based on your terrace.Collect the treated water too on the terrace and use it for flushing.

Even if you treat the water on the ground you will have to pump it to a higher level to use it for flushing, so pump up the grey water itself. The tank in the ground could be just for maximum 200 litres whose overflow can be connected to the sewage network which will also provide for the scouring velocity.

Avoid connecting the kitchen water to it, it will raise a mammoth stink!

Chitra Vishwanath
Biome Environmental Solutions Private Limited


Dear Kumaresh,

Your intention to do grey-water recycling is indeed very bold, and an ideal initiative to practice water conservation. This will be the order of the day in a few years .

There is no perfect solution for arriving at the appropriate design.
Our Ngo has dealt with waste water treatment plant using natural methods ranging from 300 litres per day to 50kl per day, and have on-site experience at Delhi and near-around. You let us know the details of flow i.e grey, kitchen waste-water, or you joining up black-water Etc. how much litres per day..we will give the details of design for implmentation, and organization & management.

There are interesting social aspects to this type of intervention, we had designed and part implemented a grey-water from baths and basins, kitchen and laundry and RO-rejct / waste- water plant, The owner of the house had intention to set up a kitchen-garden at the green-patch areas growing some edible plant-foliage, and vegetables, flowers etc..

Soon realised, this type of waste-water would contain urine and others, which was not acceptable if the flowers were to be offered for worship, and some vegetables cooked and consumed.

Hence re-plumbing and some other modifications were done to reach a level of personal satisfaction.

Right now the decentralised domestic waste-water recycling plant applying natural methods i.e septic tanks, gravel-filters, root-zone plants, fish, fountains-spray etc is going through a developmental phase and also being clubbed with eco-san elements like urine-harvesting, kitchen-compost and others .

This phase is very similar to the one desert coolers- cooling air using water-sprays went through a few years back. Now every road side artisans are making it.

All the best, have a firm will and you can do it..

with wellwishes from VigyanVijay,

Ajit Seshadri

Er. Ajit Seshadri,Head- Environment, The Vigyan Vijay Foundation


Dear Kumaresh.S,

Yes, treated grey water can be used for toilet flushing and also for drip irrigation.Grey water treatment is not as complicated as sewage treatment, but first the likely quantity that will be generated daily needs to be established. If I know the total number of residents there will be in the house that you are building, I can work out the likely grey water quantity that is likely to generated daily.

This will help decide the space that needs to be left for installing a grey water treatment system.

I believe that you also need to consider rain water harvesting seriously to augment water supply for this house.


Ion Exchange

8. Need help with recycling water in apts in Marathahalli,Bangalore

Hello Mr.Ranganathan

We live in Marathahalli and are facing severe water problems. Our apartment has 80 flats, and the plumbing restrictions make it very difficult to have a control of water usage. We were thinking using recyled water and wold like to have more information on this. Kindly let me know if you can help.



We use water for cleaning our food. This can be pre-cooking or during the cooking. We also use water to clean our body and our belongings(clothes, utensils, furniture, flooring, etc.).

Main objective of this cleaning is to remove the nitrates that cause sanitation and health problems.

So, while treating water, we also have to remove the nitrates before we can reuse the once-used water. Otherwise the nitrates will go on building up and create a loud alarm. This can be in the form of odour, pathogens or pests.

Many 5-star hotels who were told to budget their water use, started using their treated sewage for flushing. The treatment was only to reduce BOD, COD, oil(all food molecules that supply power to the alarm mechanisms), not the nitrates(real pollution issue).

With few rounds of recycling, nitrates increased and the flushing water became black due to the production of toxic H2S gas. When this water was rejected outside, it created malaria mosquitoes(that breed in high nitrates/food ratio water).

We have a project where 6 years of total recycling has been demonstarted, implying there is no build-up of pollution. The project is a Public Toilet in Mumbai, owned by the Municipal Corporation, where sewage is treated and used again for flushing. There is no water tap in the toilet. Daily about 100 people visit the toilet.

The working unit of this system is a bio-catalyst called BIOSANITIZER. 100 mg of BIOSANITIZER offers all the bio-services as offered by 1 acre of natural forest, of converting nitrates and CO2 into mixed fragrance and oxygen. The aroma repells pests, also attracts pleasant creatures such as butterflies.

For sullage treatment, provide a 3-tanks(or 1 tank with 3 compartments), system to allow digestion of both floating and heavy settleable matter. If the flow is 1000 liters/day, provide total volume of 1,000 liters.

Input can be from bath, kitchen and laundry. If the treated water is used for the laundry, it will save use of laundry chemicals, too.

This water is an asset for the garden, to keep the weeds and pests away without use of poisons, just with eco-logic. It also acts as a tonic for the plants.

One proud owner of such a system in Pune, used the water for washing their car. They got a querry whether they have got a NEW car.

When they used this water for mopping the floor, they noticed reduction in household pest population, including the mosquitoes.

Pests are nothing but 'income tax officers' of Nature. Keeping nitrates at places where they cannot be used by plants, is an eco-crime and pests come only to detect and warn us about this waste of resources.

Pathogens are nothing but microscopic pests, they come at higher nitrates.

-Dr Uday Bhawalkar

Director R&D

Bhawalkar Ecological Research Institute (BERI), Pune

10. Dear Dr. Uday.  Thanks for

Dear Dr. Uday.

 Thanks for the detailed explanation. I am from Bangalore and I have made arrangements to recycle grey water to use for flushing our toilets. but this water currently stinks. How do i remove this odour? also i am interested in using this water for gardening, car washing etc. pls can you help me out? where do i get help in Bangalore?




11. How to implement this in apartments? Please answer

Hello Dr. Uday,

I'm keen on knowing how we can implement this in our apartment building with 10 flats? The building is on a 4000sq ft plot. Your inputs will be much appreciated.



12. Suggestion for RWH and Grey water treatment


I am from a small place called Ongole , Andhra Pradesh. Close to my house there is a hostel, which is run by my neighbors.  I am encouraging them to go for RWH and grey water treatment. As the investment is high, they are not interested, how ever I am trying to motivate them, as they are buying water during some parts of summer.

The location details - plot measure 30*70 (30 North to South, 70 West to East), built up area 26*66, 2 feet on both sides set back, but slab extended to 29.5 feet, and one side the 2 feet set back cannot be used, as there is a public sewer. The  2 feet set back on the other side in North is between two buildings. The first floor is a commercial area. 2,3 and 4 th floors are PG hostel.  There is a setback of 4 ft towards the backside. There are 24 toilets in the building, which is used by 70 to 80 people. 4 toilets on north side, in between the building and 4 toilets south side. 

I am asking them to divert the shower water, hand wash water (bathing and wash basin) through a grey water treatment plant. Step 1 - Divert the south side grey water to north side through a pipe, so that all the grey water from the building can be collected in one place. Step 2 - Filter hair and other solid material, by using a 100 L plastic tank (water will flow through a plastic cement bag and fall into the 100 L Drum). Step 3- Allow the out put from Step 2 to 200 L capacity drum which has gravel at the bottom and sand on top. Step 5 - Collect the water into a temporary storage tank at ground level. Stpe 6 - Pump the water into an over head tank, which has Fishes and Tortoise in it. Step 7 - Let the water flow to flush tanks of toilets.

For RWH - Step 1 - channel all the roof water (2000 SFT), from 3 places. Step 2 - Mix the 3 out puts in a pipe.  Step 3 - Use the Rainy filter - FL 200, produced by a firm Rainy or use a filter designed by Shivakumar of IISc Bangalore . Step4- Divert the out put to underground sump, if excess, recharge the ground water

Can the undergroung sump be constructed at the space available on East of the building i.e 3 feet wide and 8 feet long?  or should they divert the excess water through drainage?


Dear Kumaresh.S,

It is quite easy to use grey-water for agriculture purpose and even for flushing after simple filtration through coarse sand filter. It is not mentioned in your query about quantity of such water generated per day. However, from the number of bathroom and size of the plot it does not appear to be large.

The simple way is to collect such water in a sump and after settlement it should be passed through slow -sand filtration. Since grey water does not contain organic pollutants, after proper filtration it can be reused for irrigation or even for flushing.


Dr P K Jha
Technical Adviser
Sulabh International Academy of Environmental Sanitation
New Delhi



Hopefully your visit to the site to see how greywater can easily be
- treated
-used for irrigation and gardening
-used for toilet flushing
was demonstrated even on a small plot of 30 feet x 50 feet

Here is a youtube film for your info:

Please also consider rainwater harvesting and ecosan if you can.




15. Is the recycled water drinkable?

Is the recycled water drinkable?

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