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Selection of Water Purification Method - Test Report Attached

I am attaching a Test Report from a local Govt. Lab that provides the service of water testing.I am NOT aware of the analytical methods/ procedures used or the instrumentation that was used to generate this test report and neither am cognizant about how reliable the same is.

Can any one briefly refer to the contemporary analytical methods used and available towards testing water for potability. The motive of this test however was to estimate the TDS in terms of its constituent composition, hence hardness of water and hence choose an appropriate RO system [pre-filter/membrance/ post-filter] that is cost efficient towards domestic usage based on the composition of hardness or water quality.

The source of water is from borewells that gets collected in a large common overhead tank and redistributed to each dwelling in a small housing colony(about 150houses).


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1. Dear User,   I have studied

Dear User,


I have studied the water test report given by TWAD Board and find that the water from the bore well is more or less within the desirable characteristics as specified by CPHEEO and which is identical to BIS-10500 the standard for drinking water as applicable to India. You need not really concern yourself with analytical tests/methods used by lab that analyzed it as they appear to have used procedures standardized by Bureau of Indian Standards (BIS). They are obviously reliable. I find that the lab has not tested for the bacteriological quality of the water OR has tested and found no bacteriological contamination.

Since the bore well water conforms to the applicable standards for drinking water in India, I would recommend no specific treatment other than filtration and disinfection. RO is not required and further, since RO can result in a lot of water wastage, I would advise against it.

Since this source of water supplies the needs of 150 houses, there is bound to be deterioration in water quality due to withdrawal of ground water unless a good Rain Water Harvesting (RWH) system is installed. TDS, total hardness and other crucial parameters will increase fairly rapidly unless RWH is done.

The users of this water should approach the Rain Centre in Chennai to install a good RWH system. For installation of a filtration and disinfection system they can approach me and I will recommend a reliable supplier.




S.S. Ranganathan


Ion Exchange


2. Dear User,   The test, if

Dear User,


The test, if generated by Goverment Laboratory, Like Tamilnadu Board, should be authentic because standard analytical procedure is followed in Goverment Labs, if there is no human error.

Perhaps Bacteriological tests were not carried out. Otherwise, chemical results are almost within permissible limits. Water can be treated as Safe for Drinking with regards to Chemical parameters.

Below 2000 ppm of TDS, generally no pre- treatment is required for R.Os. As TDS is a bit above desirable limit, any ordinary RO may be used.


With regards,


Diponkar Bordoloi

Assistant Engineer

Public Health and Engineering Department (PHED)

Guwahati, Assam


Dear User,

As per the test report attached by you, the water is fit for human consumption as far as Physico-Chemical quality is concerned. Kindly get the water tested for Bacteriological Eamination also. For this TDS of water simple R.O.filteration is sufficient, however in my opinion water with this range of TDS can be consumed directly after disinfection.


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

4. Selection of water purification method.

Dear User,

I stand by what I have said.There is no need to install an RO plant for water with a TDS of less than 700ppm.

You have a common overhead tank from which water is distributed to 150 houses.If I assume a population of 5 people per house, to get a total population of 750 people with a daily requirement of 1,02,000 litres of water (approx) based on CPHEEO standards.You will need to install an RO plant with a capacity to treat approximately 5000 litres/hour of your bore well water.Such a plant could cost approximately Rs.15 lacs plus to buy and install.Thereafter there is the operating cost to be considered which could be approximately Rs.10,000/- per day(includes cost of operating manpower,consumables and power costs).Presumably you have an association which will have to take a decision.

The cheaper option would be to say that all houses will get filtered,disinfected water(free from suspended impurities and bacteria).Those who want to install RO or whatever else they fancy should invest in these as individuals so that the cost of buying and operating remains that of each individual who buys the purification device of his choice.

I hope you will find this useful in taking a decision.




5. Water Quality- Measure of Chloride & pertinent apprehensions

Gentlemen- Thanking you both (SSR=S.S. Ranganathan & DB=Mr.Diponkar Bordoloi) for your thoughful response and suggestions, however, I would want to add the following information to clarify further...

    From the test report it is observe that Chloride = 190 Units is an anamoly per the observation & suggestion of a Solar Heater Vendor who says that the measure figure   is a bit high and needs to be rechecked - for the reason that the Vendor's Solar heater (glass pipes) would get clogged easily at this Chloride level and hence is not feasible   to install the system.

We have been used to Water supply from Municipality that is amongst the best in INDIA which has had a TDS <(less than) 100 units.

The report is characteristic of water we have been using through the last decade,       the following observations has been overlooked (a) Scaling in water containers (b) sometimes after boiling for consumpttion a thin layer of salt is suspended on the surface of the water which needs tobe filtered (c) Water in the SINTEX overhead tanks get cleaned once in 6months and due to direct exposure to solar heat, about 3 to 4Kg of salts simply gets precipitated/ sedimented at the bottom (d) a R.O. System vendor says that TDS of this range could lead to Kidney stones and other health problems which makes one to be wary having Senior and 40+ aged habitants - How true are the aforesaid health apprehensions & considerations in the light of SSR's suggestion that     a R.O. is NOT typically needed.

R.O.System [10L/hour capacity] related questions: Is a 5micron pre-filter suffice. Is    UV disinfection the only method available for disinfection along with a R.O. system or filtration system ? What is the membrance Code to be used considering DOW's FILMTEC membrances between: TW30-1812-75 and TW30-1812-100. 



6. R.O requirement



As far as my knowledge goes, you can drink water without any hesitation, if Bacteriological quality is O.K. R.O may satisfy your mental agony only, it may be used in household level.

There are several disinfection methods other than UV.

With regards.

Diponkar Bordoloi.

7. Water quality-Measure of chloride & pertinent apprehensions

Water supplies to large cities by water supply authorities such as TWAD board have undergone lots of changes over the years.Population growth has increased demand for water forcing the water supply authorities to rely on ground water to augment surface water sources(lakes or rivers).Consequently, TDS levels have started rising.A TDS of 100ppm is really difficult to find nowadays and is best forgotten.

Your water has a total hardness of 240ppm and hence there will be a precipitation of the temporary hardness when water is boiled.This will either form a hard scale or settle to the bottom of the vessel as a sediment.Tanks that store water will collect sediments over a period of time and need periodic cleaning.The sales rep of a company that sells RO systems is bound to 'scare' you with consequences like kidney stones if you do not buy an RO system! If he succeeds in selling you one,he gets a handsome cash incentive.You are most welcome to buy one and experience the 'after sales' service.It could either make you happy or very frustrated.The freedom of choice is entirely yours.

The person representing the solar heater manufacturer obviously knows very little about water chemistry.Chloride levels do not cause 'clogging',it is the hardness which causes scaling/clogging and that too over a fairly long period of time.I have had a solar heater installed at my house which is now 12 years old and it is still functioning very well.I suggest you approach a couple of other solar heater manufacturers and find out what they have to say.

You have by now received numerous comments from very knowledgeable persons.A majority of them are saying that if you take care of any bacterial contamination in your water,you do not need to install an RO.Also, I advise strongly against going into technicalities like which RO membrane to use,etc.Having been a very senior executive in a large company that makes RO systems till I retired a few years ago,I can assure you that each of them will choose the correct membrane for their RO and there are over a dozen membrane manufacturers world wide.

Water as it is now available in the country,if it conforms to BIS-10500 will not cause any problems to even elderly persons.It is the prescence of bacteria(coliform bacteria) that is responsible for water borne diseases and in some cases death.

If you follow the advice given by all those who replied you will not go wrong.Ultimately the choice is entirely yours and I wish you luck with your choice.


8. Dear User,   Contemporary

Dear User,


Contemporary analytical methods used and available: Good analysts generally use Standard Methods for the Examination of Water and Wastewater, a joint publication of APHA, AWWA and WEF.

Need for TDS treatment: There is no need to go for TDS treatment as TDS value is quite reasonable for a groundwater sample. 


Views are expressed in personal capacity.



Environmental Engineer

Pollution Control Implementation Division - III

Central Pollution Control Board

New Delhi

9. Dear User,   I do not think

Dear User,


I do not think that it is essential to install a Reverse Osmosis unit to reduce the total dissolved solids.Since the bacteriological test was not made; disinfection of water may be done only by way of caution.  Chlorination or ultra-violet exposure may be adequate for the purpose.


With regards, 


Paritosh Tyagi

Chairman (Retired)

Central Pollution Control Board

New Delhi

10. Dear User,   Get water tested

Dear User,


Get water tested for Bacteriological contamination.Please find the below mentioned Bacteriological Standards:

  • For water entering a distribution system- Coliform count in any sample of 100 ml should be zero (0).
  • For water in a distribution system – (i) E Coli count in 100 ml of any sample must be zero (0). (ii) Coliform organisms should not be more than 10 per 100 ml in any sample. (iii) Coliform organisms should not be present in 100 ml of any two consecutive samples or more than 5% of the samples collected for the year.


The other parameters are OK.


With best regards,


Abhishek Mendiratta


Water Resource

New Delhi

11. Dear User,    IS 10500:1991

Dear User, 


IS 10500:1991 Drinking Water (First Revision) may give you the useful information in this regard.  The scope of this standard is as follows: 

'The standard prescribes the requirements for the essential and desirable characteristics required to be tested for ascertaining the suitability of water for drinking purpose.'

Food and Agriculture Department is dealing with the above subject and you may contact this department for further clarifications.


With regards


B. Sandhya


Chemical Department

Bureau of Indian Standards

Government of India

New Delhi

12. Effects of Hard Water on human physiology

 Ladies & Gentlemen, Thank you all for your clarifications and responses...One aspect other than bacterial test, is the Clinical Study of Hard Water consumption     or of its external usage on human biological system in general.


 Is usage of water Hardness for bathing a major cause for Hair fall? Has there been any other Clinical studies on the physiological symptoms on Hard water usage for consumption or externally?

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