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Waste water treatment systems in apartments

Many apartments in cities are setting up waste water treatment plants to recycle  waste water and use it for non-potable purpose.

What are the various systems available in India?

What is the average cost of treated waste water per kilo-litre in each of these systems?

Vishwanath Srikantaiah

The Rainwater Club,





Dear Viswanath,

An apartment of say 100 houses discharges a quantity of waste water, say about 300lit per day per house, i.e 30,000 liters in total.

A DEWATS plant having a capacity of 10kl per day costs Rs. 2.5 lakhs, hence this will be 3 times for this case i.e 7.5 lakhs.

The monthly cost of 3000/- on electricity and 2000/- for 1 or 2 mali/gardners to work regularly on the plant is needed.

Including the depreciation cost of Rs.7.5 lakhs for 10 years works out to Rs.6250/-month, Rs.5000/- pm for the monthly cost of operation and 5% per year for maintenance after 3 years works to Rs.3125/-, the total cost of maintenance per month works out to Rs.14375/- per month. Therefore, for the 900kl of water processed every month, the cost of treating one kl of waste water works out to Rs.16/-

The details are based on the waste water recycling plants using DEWATS technology implemented by us in Vasant Vihar, New Delhi and as well as in other locations.


Er. Ajit Seshadri
The Vigyan Vijay Foundation, New Delhi
Website :


We have only very briefly touched upon this when we met at Arghyam's office in the past.Ion Exchange(India)Ltd manufactures Sewage Treatment Plants of a wide range of capacities.There are some installed in and around Bangalore which could be visited for a first hand look.The systems are compact in view of space being at a big premium.The STPs occupy approximately 30% of the space occupied by a conventional activated sludge based design.
I notice one of the responses has given a very detailed break up of operation & other costs.The systems I am talking about would have similar operating costs.Please feel free to call me any time if you want to discuss this further,my number is 9343734229.
Business Adviser
Ion Exchange Services Ltd



For Sewage or wastewater treatment for residential buildings or apartments, there are certain issues to be addressed while designing a system as under:

• The system must be compact so that it occupies minimal area. This is because apartments have hardly any area to spare for STP.
• The system must be such that there is no odor around it. This is because it may be located in the car park (underground) or in the garden area where kids play.
• The system must be closed so that there is no open sewage that is bad to look at and there are no germs flying around the open system.
• The system must be aesthetic in appearance: something like a silent DG set versus a normal DG set which invariably looks like a monster ready to eat.
• The system must be such that it could be shifted or relocated as and when required. Managing committees are known to change locations of various items in such apartments at will.
• The system must have minimal power consumption.
• The system must be able to run at less than 24 hours operation unlike most systems which run round the clock and cannot be shut.

The above criteria are used for having such a system. The best known technology in India is the MBBR or mixed bed bio-reactor. The operating cost for such a system may be Rs. 5 per cum. Capital cost for a 50 cum/day system may be about Rs. 16 lakhs, all inclusive.

You may contact us for more details.

Taral Kumar.
Akar Impex Pvt.Ltd, New Delhi


Our thanks to Water Digest magazine ( for providing this answer -- Moderator
) for providing this answer -- Moderator

Generally for large apartments the water requirements are used for drinking, bathing, cleaning, etc. and the raw water available is normally groundwater which constitutes excess minerals (TDS is very high). Therefore for drinking application we require RO plant and for cleaning, bathing, etc. one can go for Water Softening Plant. Which removes the hardness from water and the scaling will not form in the pipelines and cleaning of clothes; even utensils can be done by this. If the TDS of raw water is under the limit of drinking water standards (IS10500) then Ultraviolet water treatment plant can also be recommended..

Apart of this in large apartments, Sewage treatment plant can also be one option to re-utilize that sewage waste/toilet water for various applications such as gardening, cleaning etc.

2. Many apartments in cities are setting up waste water treatment plants to recycle wastewater and use it for non-potable purpose. What are the various systems available in India?

Now a days, there are plenty of options available in the market such as Sewage treatment plants, RO plants, UV treatment, Normal Filtration plant such as Pressure sand filters, Activated carbon filters etc.
The selection of any of the option totally depends upon the raw water quality available and the final application of treated water.

3. What is the average cost of treated waste water per kilo-liter in each of these systems?

The average cost of treated waste water comes around Rs. 8 to Rs.15 per Kilo-liter .(excluding plant basic cost). However exact cost can only be determined after finalizing the following:
i) Raw water quality
ii) Product water quality

iii) Total water requirement

Aniruddh Gupta
Water Digest Technical Expert & Sr. Engineer - PSE
Doosan Engineering & Services India Pvt. Ltd.;


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Our company has developed a Package Sewage and Effluent Treatment system in collaboration with US based firm. These Package Sewage and Effluent treatment plants known as AEROFLOW system are prebuilt at factory and can be installed directly as an equipment with minimum of supervision.
The benefits of packaged Aeroflow Sewage and Effluent Treatment supplied by us have the following advantage.

• Compact Footprint.
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These Compact package Sewage and Effluent treatment system are suitable and beneficial to Hotels, Hospitals, Resorts, Housing Colonies, Multistoried apartments, School and college buildings, small and medium size industries and other similar institutions.please visit for more details.
for more details.

Sathishvelan - Engr. ( Marketing )

6. Need solution for our apartment

Can u suggest your system for our apartment use with a daily approx. discharge of 8000ltrs into the septic tank.

Thanks and regards

7. Sewage treatment - in-house cultured microorganisms

We focus on treating waste by using special in-house cultured microorganisms that are "probiotic" in nature and absolutely eco-friendly.

Septic tanks only partially treat sewage, discharging polluted water leading to ground water contamination. Also, septic tanks without proper treatment get clogged & filled with sludge which leads to frequent pump out by tankers which is a huge nuisance and unhygienic practice. Soak Pits get choked when their percolation action is hampered due to sludge and grease deposits.

We have solutions that utilize the existing tanks to treat the sewage using our special microbial culture. You can recycle treated water for gardening or discharge it into the ground water through the soak pit. Your existing septic tank can be utilized and modified (if required) to treat the waste water in an Eco-friendly and cost effective manner.

We would require the following details from your end to suggest a way forward - 1. Daily Flow of waste water (combined from toilets, bathrooms, kitchen , laundry etc) 2. Dimensions of Septic Tank Regards,

Kush Agarwal +91-98998923242


Though there are several solutions existing and they are all good, but they are based on using a centralised system of sewage treatment and for get the age old wisdom in using Septic Tanks.
By using Septic Tanks, you avoid the need to put in sewer lines (unless the sewer line also works as the rainwater drains). But the main problem arises of the disposal of the large quantity of treated water at the centralised plant, which is notmally about 100+ cu. mtrs. per day.
If you have individual septic tank(s) or for a cluster of houses then you could use the treated water, locally within that segemnt, either by discharging into the ground or re using it for horticulture etc.

Keshav Agarwal


i agree with Aniruddh Gupta,Water Digest Technical Expert & Sr. Engineer - PSE
go for a STP followed by disinfection and filtration to reuse treated water except for drinking/u can have my free service at

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