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STP effluent water:Use in Construction?

Is it possible to use the treated water coming out of a Sewage treatment plant in construction purposes? Hirco is working on an integrated township near Sriperumbadur in Tamil Nadu. The project would come in a number of phases. As the first phase gets completed, the other phases would follow; We will need large quantities of water for the construction of aparments, shopping centres, hospital, school etc. Hence I would like to know if the STP treated water can be used in the construcion of builings.





The fact that treated water coming out of a Sewage Treatment Plant (STP) is being considered as a source of water supply for the construction of a township near Sriperumbadur indicates that no other sustainable source could be identified for the proposed township. It is no doubt possible to treat water from an STP to such high standard as to use the treated water not only for construction but also later to serve as a source of public water supply to the township. Although use of treated water is not uncommon for various uses including drinking in developed countries and for industrial use in India, such usage for drinking in India may be resented.

Before planning for a township, my suggestion to Neelakantan is to take up detailed hydrological and hydrogeological studies in and around the proposed township to ensure the availability of both surface and ground waters of adequate quality and quantity to meet the water needs now and in future. Treated water from STP may also be used for construction besides using it later as a supplementary source of water for non-potable uses.

Dr. R. Jagadiswara Rao
Former Professor of Geology
Sri Venkateswara University
Tirupati, AP 517502

Dr. R. Jagadiswara Rao, Professor of Geology Retired, Sri Venkateswara University, Tirupati, AP 517502, India


dear neelakantan,
this indeed is a good option of recycling water for consruction purposes, only periodically check the functioning of the STP. A retention time from the time water is discharged from user's point till it is at ready to use mode after the last stage of STP, a retention time to be around 8 to 10 days for keeping the water in healthy order, large pond systems are possible with aquatics to accept STP effluent water and store/ get up-graded naturally and taken for re-use for construction. Rain harvested water can also be stored in the planned water-bodies etc..
It is in order to use STP Effluent water only ensure good functioning of the STP.
ajit seshadri

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


Dear Neelakantan,

I apologize for this habit of mine of first passing every question through a filter to see if the question itself makes sense. There are two inexplicable things about your question.

a) Construction water is a one time need. You would need much larger quantities of water, and need it for ever, year after year, for use by the occupants of the integrated township. Surely the township would have been planned only after ensuring availability of this water ? Then why is there a need to use STP effluent for construction ?

b) It is not as if you are a layman individual, constructing a small bungalow of your own. An integrated township project would have their own site laboratory and personnel expert in concrete mix design and such. Then why this call for help in IWP ?

A township project would very likely use a centralized concrete mixing plant; where additives would be used to slow the setting process of the mix while it is transported in transit mixer to the site. Very slow reaction of some constituents of water, aggregate, cement and various additives is a complex question in the domain of chemistry of construction materials, and has nothing to do with “water sector” in the conventional sense. Therefore, some of the answers you may receive on this forum - driven by a zeal to “save our scarce water resources by recycling and re-use” – may not even be correct, and I advise you to be very careful of such answers.

The question can only be answered by experts in construction materials, not by hydrologists like me. I am referring it to CSMRS (Central Soil and Materials Research Station) and will revert back if and when they answer. Or you can refer it to the Civil Engineering Dept. of IIT-Chennai (nearest expert center) for advise on a commercial basis – not “gratis” - and tell us what they say.

Chetan Pandit
National Water Academy


I don't agree with the statement of Chetan Pandit that "some of the answers on .. (India Water Portal) – driven by a zeal to “save .. scarce water resources by recycling and re-use” – may not even be correct, and .. (one should) be very careful of such answers".

His contention that the Hirco township project can get the necessary advice from the Central Soil and Materials Research Station (CSMRS), an attached office of the Ministry of Water Resources, is also not correct in view of CSMRS specialising in geomechanics, concrete technology, construction materials and associated environment issues in respect of river valley projects and connected structures in India and abroad

Hirco, a sister concern of Hiranandani – one of the largest real estate developers in the country in the past 25 years – was formed in 2006 to co-invest in large scale mixed-use township developments in suburban areas outside city centres in India Its first venture is at Sriperumbadur near Chennai. Hiranandani has taken up 100% sewage recycling and rain water harvesting in all their properties since 1989 with the twin objectives of water conservation and clean environment.

Despite his company having a large fleet of engineers, Neelakantan has appoached WES-Net India and India Water Portal for advice evidently because of the popularity 'Ask A Question' Programme has gained in providing scientific solutions on water problems at individual, community, industrial and other levels.

Dr. R. Jagadiswara Rao
Retired Professor of Geology
Sri Venkateswara University
Tirupati, AP 517502

Dr. R. Jagadiswara Rao, Professor of Geology Retired, Sri Venkateswara University, Tirupati, AP 517502, India


I am surprised to find experts in IWP rushing to endorse use of STP effluent for construction without asking for a chemical report of the STP effluent in question, or without advising what to watch out for in such report, and with vague remarks like “periodically check the functioning of STP”. Check for what parameters ? Here are some comments onthe chemical composition of the water used for making concrete.

Alkali-aggregate reaction is a chemical reaction between certain types of aggregates and alkalis. Usually, the alkalis come from the cement but they may also come from other ingredients in the concrete, which includes water, or even from the environment. The reaction may result in slow but progressive damaging expansion and cracking of the concrete.

High amounts of suspended solids in the water can increase dry shrinkage and can cause excessive leaching of salts which increases porosity and decreases strength. Certain dissolved salts can cause slower setting and hardening times, reduce the strength, and increase the risk of corrosion of reinforcing bars. Certain organic materials even ion very small quantities may retard hydration and entrain excessive amounts of air into the concrete.

There are BIS standards and also text books regarding quality of water used for concrete.
CSMRS is not only an expert organization on this topic, but the apex national organization in this area. Neelakantan may also seek advice from civil engineering departments of a nearby reputed engineering colleges; or private test houses like Sriram Industrial Research Institute, etc.

Further, they should ensure that they seek advice from one who is an expert in concrete chemistry, and not from us water budget managers. e.g. if they go to the civil engineering department of an engineering college, they should go to professor of RCC, and not professor of hydrology.
Chetan Pandit
National Water Academy


Further to my reply on 9th April 2008, the answer to the question posed by Neelakantan can be best obtained by contacting the Bangalore Zonal Office of the Central Pollution Control Board (CPCB), whose address is given at

The status of sewage treatment in India with the gaps existing between sewage generation and treatment capacity, technologies used for sewage treatment and performance and efficacies of the existing sewage treatment plants can be known from and

Details of a project implemented by the CPCB at Auroville in Pudichhery (Pondicherry) to treat and use domestic wastewater from the households at a residential colony for emulation can be obtained at

Dr. R. Jagadiswara Rao
Retired Professor of Geology
Sri Venkateswara University
Tirupati, AP 517502

Dr. R. Jagadiswara Rao, Professor of Geology Retired, Sri Venkateswara University, Tirupati, AP 517502, India


Dear Neelakantan,

STP treated water is 100% possible to use for construction purposes.Bio products are available to treat STPs which are economical and easy to use.
Treated water with Bio products will have:

1.No odor(foul smell) Odor will be 100% removed.
2.Reduction in COD/BOD/TSS/Bottom Solids.
3.Visibly clear water will come out after the treatment.

With regards
Hiren Pancholi

8. Can we use STP water for irrigation?

We need your opinion about using STP water for irrigation, since the water is treated by plants along with chemicals. I have a big doubt whether it can be used for the same.
Please suggest and start a discussion about STP water being used for irrigation purpose.

Thank you gentlemen!

9. Can we water plants with treated water having oil/grease content


If the STP outlet water has all the values under control like pH, TDS, BOD & COD within the permissible range and only oil/grease content is in the range of 4-5 ppm, can this be used to water plants in a normal process through MS pipeline.

Thanks & regards

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