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Discoloration & Foul Odor: Rejuvenation Possible? Test Report Provided - Bangalore

I have an open well in the North east corner of 60x40 site facing west. We are having this well right from 1970 when we constructed the house. The well must be around 12 rings deep which means around 24 feet from the ground and has good water level (top surface being 3 to 4 feet below normal ground level) during rainy season and has around 5 to 7 feet of water (2to 2.5 rings depth) during summer. we have used this water earlier for building purposes (for the neighborhood) and for our gardening etc. Occasionally we have used it for drinking and cooking long back.

But now for the past 2 years the colour of water has become blackish and also the water has a foul smell. The walls of the rings are black in colour but when pumped out the water appears clean with no foaming but with foul smell. I got the the whole water pumped out once last month and got all the marsh cleaned.  The person who went down for lifting the marsh tells me that the water inflow from the side holes of rings at the bottom is free of smell. But after a month I got the water pumped out again recently and found the water to be again black in colour and with smell.

I would like to get the whole water cleaned and install a pump and pipe to use the water for gardening etc. Can some body suggest me a solution to have the well cleaned so that I can restore the well to what was 2 years back??

The test report of the well water is attached.

The house is in HAL II stage (Indiranagar) Bangalore.






Dear Ramachandran. K.S,

Information is lacking on the likely sources of contamination of water. However, a depth of 3 to 4 feet below ground level is actually quite shallow to be reliable. The bacteriological analysis clearly shows that the water is unfit for consumption without disinfection. The black colour and foul smell may be due to a nearby drain containing foul matter overflowing or seeping into the well depending on the construction of the body of the well.

With regards

Paritosh Tyagi
Chairman (Retired)
Central Pollution Control Board
New Delhi


Dear Ramachandran. K.S,

Your open well is a shallow one. There must be constant contamination from percolating contaminated water, sewer or any other nearby source of biological contamination. Chemical parameters are o.k. but one should not use water from such source (highly biological contamination) for drinking purpose and any other purpose where there is risk for fecal- oral route of transmission of disease.

Standard procedures of source disinfection are available in Water Supply Manual (CPHEEO) and other books. But the point is that you must block the nearby external source of contamination. Otherwise, source disinfection would not serve the purpose. In case, you need the disinfection procedure you may consult the manual or directly contact me through e mail.

With regards,

Diponkar Bordoloi
Assistant Engineer
Public Health and Engineering Department (PHED)
Guwahati, Assam


Your open well is a shallow one. There is possibility of sewage contamination from any nearby leaking sewer pipe. Possibility of existence of open field toilet in an area like Indiranagar is unlikely. This contamination may be one time (when the water table rises high) or may be a slow continuous process.

If you want to continue using it, then clean it with bleaching powder and then keep on monitoring it every fortnight. Just check for bacteriological test. That is not so costly. In case there is a change in the MPN number you have to conclude that this water is getting contaminated by sewage.


Dear Ramachandran ji,

As per the test report attached all the chemical parameters are within the acceptable limits. The problem is the presence of Feacal & E.coliforms. The reason of foul smell is due to the presence of these coliforms. You should disinfect your well with chlorine.

First you should clean the walls and surface with the paste of bleaching powder and then treat your water with 5-6 ppm of chlorine dose. For calculating the quantity of bleaching powder you should know the quantity of your well water by using the formula

D(square) xW x 5 x4.55 = liters of water (D-diameter, W-Depth of water). For One lakh liter of water you should use approximate 1.5 kg of bleaching powder for 5.0ppm residual chlorine.

It is better to Chlorinate your water in the night. I hope this will resolve your problem.

Amit Kumar Singh,
Water Testing Lab, Karnal_132001(Haryana)

Amit Kr. Singh,
Govt. of Haryana,
Public Health Engg. Department,
Water Testing Lab,Karnal-132001(haryana)


Dear Ramachandran,

Attached reports shows the analysis of water samples in Feb and August 2009. First report is on physical and chemical parameters (Chennai laboratory). As per the results, TDS is very high. (Please check whether this is report of the well water sample).
Second report is on the bacteriological quality. Total coliforms, fecal coliforms as well as E.coli 9 Highly specific for human excreta contamination) are present. This definitely shows that water is contaminated by sewage.


Leela Iyengar

6. I agree with Paritosh

I agree with Paritosh Tyagi,the bacteriological analysis clearly shows that the water is unfit for consumption without disinfection. The black colour and foul smell may be due to a nearby drain containing foul matter overflowing or seeping into the well depending on the construction of the body of the well.

Maris K

7. Suggestion for well problem

I have an open well in Raichur City of North Karnataka region. It is a very old well which was constructed using big size stones blocks on all four sides. The size of the well is : Length-23 x Breath-12 X Depth - 30 feet.

The water level has come down to a great extent i.e, it has only 3 to 4 feet of water available at present. My questions are:

1. How to increase the water level in the open well?

2. Will it be useful for me if the depth of the well is increased to another 2 to 3 feet?

3. Or it will be useful for me if to dig a bore well in the open well?

Please suggest the best option to solve my water problem. 

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