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Confusion regarding yield & depth: Borewell Drilling, Hennur - Bangalore

I am currently digging a 6.5inch borewell in Hennur area in Bangalore. Water diviner has said i need to go to 700ft in order to get 2inch water yield. However the borewell company has told me that at 500 ft I have achieved a 1inch yield and that i should stop drilling at 550ft. They say that if i go further down then the yield will decrease. At the moment i cannot see any water coming out and they are saying that is because it is all evaporating due to high temperature.

Can you please advise me on when i should stop drilling? What should i be looking out for during drilling.

Thrivikram Naidu




Deae Thrivikram Naidu,

If no water coming out while drilling is going implies that the bore well is dry. You need to drill further. As per the information, I used to get from drillers in your area, if you miss a water striking zone, between, 380 -430 feet then you get a chance between the depths 720-750 feet only. Hence you may take a chance. Scientifically, can it be recommended? Kindly note that, to the best of my knowledge, as on today, there is no scientific method exists, to answer your quarry.

However based on the statistics of successful bore wells it is possible to establish solution to similar cases.

If any research have already done in line with information Theory to apply to similar cases, then professionals should come out or they may have to be elucidated. It has become quite common practice, to drill beyond 1000 feets and beyond.
The depth of investigation of normal resistivity theory may not address to such problem. Even the, inverse theory, will lack resolution, at a depth of 1000 feet and beyond. If we see the live bore wells with huge discharge are these deep bore wells.

With regards,

A.Rajamohamed Ambalem
Coastal Energy Private Limited
Chennai - 600006


Dear Mr.Naidu,

In my opinion it is not possible to be 100% sure of the yield of the well before drilling, it is your decision to take the risk and inform the drilling company to drill upto the depth you need.

I do not understand what you mean by water is evaporating and not coming out, when you say you have got 1 inch water yield.

When to stop drilling - If the type of stone you are drilling is very hard there is no scope of obtaining water by further going deeper unless proved by hydrogeological report that there is a second aquifer at a lower level ( or based on borewells report in the near by vicinity)


Dear Thrivikram Naidu,

There is every possibility of water loss during the drilling in progress. The case explained by you is related with low yielding bore well, hence further drilling of bore well depends on the study carried out by water diviner and its recommendation. If a proper ground water investigation has been carried out by adopting scientific methods than there is need to refer the case with details of survey data. These information will help in giving the proper guidance.

With regards

S C Jain
Programme Coordinator
Action for Food Production (AFPRO)
New Delhi


Dear Tasneem Raja,

Normally in hard rock areas water is found in secondary porosity i.e in joints & fractures. And at a depth of 700 feet chances of getting good fractures are remote therefore no point in going for further depth and drilling can be stopped at five hundred feet. Further I would like to clarify that at the time of drilling due to high drilling pressure the discharge of water is less than its potential. And once drilling is completed and well is properly developed discharge would definitely increase.

Further, it is always suggested to go for electrical resistivity survey prior to drilling to avoid confusions related to final depth of bore well as we can always find the potential ground water zones occurring at different depths through resistivity survey

With thanks and regards,

Dr. Asad Umar
Programme Officer
WaterAid (UK)-India Liaison Office West
Bhopal, Madhya Pradesh


Dear Tasneem Raja,

Bore well depth has no relation to discharge. It is only the fractured zone that yields water. I think 500 ft. is sufficient to meet the required ground water demand as far as domestic requirement is concerned. It is not advisable to spend unnecessarily for drilling further.


D. Chakraborty
Central Ground Water Authority (CGWA)
New Delhi


Dear Thrivikram Naidu,

Yield depends both on depth and type of geological formation. If your aquifer (bore well) is in hard rock then there could be an increased yield if there is a thick fracture exists underneath otherwise there is no use in deepening the bore well. You can verify this by requesting a Geologist/Geophysicist by carrying out electrical resistivity survey.

If your aquifer is in soft rock for example sand stone aquifer, then yield could be increased because of its depth and thickness of the aquifer. I can not agree with water diviner's suggestion that yield could be increased just by deepening the well. Kindly contact a hydrologist of CGWB at Bangalore and discuss with this problem and they can provide a viable solution.


Dr. M. Thangarajan
Retired Scientist-G
National Geophysical Research Institute (NGRI)

7. Need help - found only silt while we tried to drill a borewell

While drilling borewell, the driller did not inform me, that he found only silt. He simply stopped drilling at 435 feet and told me it wont be possible to drill further.

8. Bore 410 feet, water yeild stopped -Another bore just 30 ft away

We stay in Raichur, around 6 months back we dug 3 bore wells out of which 2 failed (which were 270ft deep) only one that is 410 ft deep yielded water and we could draw water for 40 mins after every 5-6hrs in 1st month later gradually yield got better, but now the yield has suddenly stopped and we can drain only for 5 mins after 12hrs.

We don't know the cause for drying out of bore well. Is it because our neighbor has dug one with very good yield at 400ft and it is just 30ft away from our borewell or is it because our source of water is drying out.

Please help, do we have to redeepen the existing bore?

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