I do not feel drinking water upto 2000 mg/L is acceptable for drinking. Such high salt concentration will lead to health hazard. Moreover my query is whether drinking water collected from purifier with RO having TDS less than 20 ppm is suitable for drinking. Will it not cause any mineral deficency?

The permissible limit as provided by World Health Organization (WHO) is 500 mg/l.

Yes, I do agree to this point. The next part of my query is to know whether we can accept water with TDS less than 30 mg/L for drinking purpose. If so will it not cause any mineral deficiency? My intention is to know at present many reputed companies supply water purifier with RO which gives less than 30 ppm TDS. How can we accept it. By paying huge amount for a water purifier we may land with another critical problem - i.e. mineral deficiency. I will appreciate to my friends in RG to think of this issue which will give a good lesson to common man 

Thank you Dr. Abhishek. I have gone through this link. It is really a good debate. But we have to think deeply from scientific point of view. 

500 mg/L is the limit of  TDS for Drinking water stipulated by WHO as well as BIS.

500 mg/Liter of TDS  for potable water as stipulated by WHO is not a limiting content on lower side. In a broad sense if unusable minerals are removed in RO process, it is no harm to use it for drinking purpose. As such, the purer the safer. The required minerals for human body may be available from food & diets. This is only a technical aspects of analyzing the issue. 

500 mg/L as suggested by WHO

Permissible limit of TDS  in India is <  500 mg/lit.   This is fact TDS is reduced by using Reverse Osmosis ( 30 - 60 mg/lit ).  In concerned with minerals  after RO is useful to study.

Dr. Sahoo,

A thought provoking question from the point of consumers.  When we opt for something which is against the nature, surely we must compensate for this.  In India, three kinds of water is supplied for consumption: surface water, groundwater and a blend of surface and groundwater.  In all the three, normally after the treatment TDS is brought down to less than 500mg/l.  There are exceptions to this.  Places which are not blessed with surface water resources, entirely dependent on groundwater and no facility for the water treatment, no piped water supply, water may be brackish with TDS more than 1500mg/l.  Surely the water will be enriched with nutrients.  When you go for RO or any other mechanisms to bring down the TDS content, one should be prepared to compensate the loss of nutrients  to human body by supplements.  As far as my knowledge goes there is no prescription as to the minimum value of TDS in drinking water.  

As much I know below 150 tds is not good for health. Most of water supplier supplying less than 100 tds and pH less than 7. As per the body requirement, TDS should not be less than 150 and pH 8.

Drinking water is taken for adequate fluidity of food we eat in a day so that it can be easily digested. No extra minerals is expected from drinking water to supplement our body needs. It should be extremely pure and free from suspended particles with less than 20 jtu of turbidity. TDS 75 to 90 ppm is ideal for drinking purpose.

Drinking water also provides a medium or channel to extract impurities from the human body. For this purpose it should be pure enough in terms of TDS to capture maximum impurities from the human body. Thanks

According to the BIS, the ideal TDS for drinking water is below 300mg/L and the max permissible limit is 600mg/L. It is recommended that people with kidney problem should drink pure water having TDS level below 100 mg/L for better recovery.

500 mg/Liter of TDS .

The RO water is recommended whenever the drinking water quality parameters are not as per standard or exceeding the permissible limits. If we are talking about total dissolved solids, it also depends on all other parameters. So the TDS value should vary according to all other parameters.

I believe that one of the shortcoming in many international standards of water quality is the minimum permissible lime of TDS. For example Who states that the permissible limit for TDS should be 500 ppm or lees than 500 ppm but what is the minimum permissible limit? Certainly, it is not good for our health to drink water with TDS = 50 or 10 ppm.

According to World Health Organization, TDS level less than 300 mg/litre is considered as excellent, between 300 and 600 mg/liter is good, 600-900 is fair, 900 -- 1200 is poor and TDS level more than 1200 mg/liter is unacceptable.

I am a Water Chemist worked in this area for more than 39 years. 500 mg/L is the TDS limit for drinking water. If no any quality of water is available this limit can be extended or allowable upto 1000 mg/ L. My suggestion and as well WHO never drink water having TDS less than 100 mg/L. By drinking such waters we will be loosing essential minerals for the body which is normally removed by RO.

Dear Raja Mohan,

Thank you for your reply and suggestions.

You will appreciate that water with ultra pure having TDS 70 to 90 is a good taste like a running river (Mahanadi)water quality what we get at Bhubaneswar Municipal corporation, in Odisha. With TDS more than 140 , it tastes like a ground / bore well water with enormous dissolved solids, like hard water and having less foam. As such we derive our essential minerals from our food and balanced diet. This purity of water may be able to clean our body by dissolving more impurities from our body system.

Can you please quote any practical problems faced by users of ultra pure water?

Thanks. [email protected]

Dear Dr Parashuram Sahoo

TDS (mg/L) < 500 : Desirable for

500-1000 : Permissible for drinking

1000-3000 : useful for irrigation

> 3000 : Unfit for drinking and irrigation

References

Davis SN, DeWiest RJM (1966) Hydrogeology. John Wiley & Sons, Inc., New York, 463 P