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Water Quality - Measures to be Taken: Test Results Provided - Kerala

Water quality test of new borewell - any measures needed? Results provided.

I did a recent test of my  new borewell water which returned the following results:

Total dissolved solids = 62 ppm

Total hardness = 44 ppm

Chlorides = 6.81 ppm

Ph = 6.7

Flouride, Sulphates, Nitrate, Nitrite , Ammonia and Residual free chlorine = nil

Iron = 0.2 ppm

Most Probable Number of bacteria = 90 /100ml


1.Is this water suitable for drinking as it is?

2. Does a UV filter need to be installed.

3. Will addition of 2.5 gm/bleaching powder per 1000L domestic tankful be enough  for drinking purposes (without a filter).

4. Is this water suitable for bathing and cooking untreated?

Thanks in advance for your answer.

Dr. Biji Thomas George,

Trivandrum, Kerala





Dear Dr. Biji Thomas George,

This water is perfectly alright for drinking, however, presence of coliform needs to be addressed for which chlorination or UV treatment as proposed can be good options.

Dr. R.C. Trivedi
Chief Environment Scientist
DHI (India) Water and Environment Pvt. Ltd. New Delhi and Ex-Additional Director & Incharge, Central Pollution Control Board

2. What is the residual chlorine level in Indian water supply

Dear Dr. R.C Trivedi,

I want to know if you have any information about the maximum 'Residual Free Chlorine' that is found in Indian municipal supply water at household level?



Dr. Biji Thomas George,

The water tests that you have given indicate that the water from chemical aspects is of good quality and drinkable.

The only thing that is disturbing is the bacterial count... this is very high.

But as you have mentioned that this sample is from a recently drilled borewell, which may have been fitted with a new pumping system, and like almost every one else who gets a borewell drilled, the borewell has not been subjected to the initial dose of Clorination before the test was conducted.

Normally any well will show a high bacterial - ecoli count if subjected to testing without initial chlorination.

The reason for this is the probability of contamination of the source due to the foreign components lowered in the borewell have been handled by humans.

Ideally after the new pump is installed, a high dose of chlorine is to be introduced in the well, the well to be pumped and the water again diverted back into the well for about 10 minutes. This ensures the system gets chlorinated both from inside as well as outside, this will take care of any biological contaminants which get introduced while installing the pumping system.

And then after a pause of nearly 8-10 hours the well should be subjected to regular use and the water should be subjected for bacteriological testing only after about 20-30 days of regular use so that the effect of chlorination is over.

by the way E-coli in itself is not harmful, but is an indicator to the presence of other bacteria which thrive within the the same environments.

I will advise you to pump the well for some time before you think of any long term remedial solution.

But a chlorination dose on a regular basis directly in to the borewell will not be harmfull at all.


Dr. Anil Lalwani


Thank you Sir for your reply.

My main concern is however: Does Most Probable Number of Bacteria correspond to Fecal Coliforms or All types of Coliforms.

As I understand - general coliforms till 100 /100ml does not require filtration as they are not associated with water-borne diseases. Please correct me if I am wrong.
I also understand there is no easy way to differentiate between Fecal and General Coliforms.

Also, what is the status of this water as regards untreated use for bathing and cooking?

Thanks in advance.


Dear Dr. Biji Thomas George,

Since the water is from a tubewell and is of such good quality, the MPN may be as a result of handling with unclean hands or utensils. However, chlorination, as proposed should be adequate safeguard provided the bleaching powder is stored in a manner that it does not lose chlorine contained by it. There is hardly any risk in using it for bathing or cooking.

Best wishes

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


Dear Dr. Biji Thomas George,

Sample water is not fit for drinking or cooking. It is highly contaminated wit biological contaminants. It is advisable not to use it for ablution purpose.

In case of treated water with Bleaching powder, residual chlorine should be within 0.2 to 0.5 ppm.

Bleaching powder has 33% available Chlorine but for practical purpose it may be taken as 25 to 30% by weight of B.P.

It becomes difficult to say anything without testing residual chlorine. You may try to find out the Chlorine demand of your sample. It is very simple test.

However, as a thumb rule you may try with 3 to 4 mg of B.P per Litre (with available chlorine around 1mg per Litre). But I strongly suggest determining Chlorine Demand of your sample.

Because excessive Chlorine in water may lead to THM in presence of organic impurity. This is carcinogenic.

With regards

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


Dear Dr.Lalwani,

Thanks for your response.

It was certainly enlightening.

Could you please elaborate on Chlorination of a new borewell or give some links to the procedure?

My borewell is about 250 ft deep with water level starting around 20 feet.
6 inch PVC pipe till rock bed (around 50 feet) and rest is 4 inch pipe.
The pump is at 200 feet depth.

Details of how much chlorine (and in what form - Bleaching powder or Sodium Hypochlorite) and duration of running the pump in cycle would be much appreciated.

Thanks again.

Dr. Biji


Dear Dr. George,

With respect to inorganic constituents, bore well water seems to be excellent. In fact it is surprising that bore well water has such a low TDS and fluoride is nil.
Regarding most probable number of bacteria, specification whether it refers to total coliforms or thermotolerant (bacteria of fecal origin) is important. 90/100ml is high .As the bore well is new, you have to get the water analysed after a month or so and then install the UV treatment unit. Presently you can boil the water for drinking and cooking and use bleaching powder treatment.


Leela Iyengar


Dear Dr. George

You have chemically excellent quality of water. The similar water is available in Konkan belt also. The acidic pH indicate the presence of laterite soil.

The high MPN number requires exploring the possible source that contaminates the bore well.

You may install any domestic water filter with UV light for drinking source.

I will recommend to add liquid chlorine into the tank. 1000 l of tank will require 2 gm of chlorine that will be equivalent to 25 ml of 8% Sodium hypochlorite.

Please call if you need any further information

Prof. R. V. Saraf
Viraj Envirozing India Pvt. Ltd.

21 Radhakrishna, Near SBI
Paud Road, Pune 411 038
Tele/Fax: (020) 25433445
E Mail:


This forum is really helpful and I am amazed at how senior and busy consultants find time to respond in such a timely and appropriate manner.

Dr Lalwani brought up the concept of chlorination of a new borewell.

However I have not been able to get any help or information on this on the net or this board.

Could anyone please elaborate on Chlorination of a new borewell or give some links to the procedure?

My borewell is about 250 ft deep with water level starting around 20 feet.
6 inch PVC pipe till rock bed (around 50 feet) and rest is 4 inch pipe.
The pump is at 200 feet depth.

Details of how much chlorine (and in what form - Bleaching powder or Sodium Hypochlorite) and duration of running the pump in cycle would be much appreciated.

Thanks again.

11. Safe source of water

Safe source of water must be ensured for people. It is important to save people from water poisoning. So, the government should take all the necessary steps to solve this problem.

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