What should be the permissible limit of TDS in drinking water?
While using purifying system with RO for collecting drinking water, the water in many cases shows very low conductivity even less than 30 microS/cm. So TDS is much less. Whether such water is suitable for drinking? Will it not cause any mineral deficiency. Many manufacturers claim that they maintain controlled TDS in water but in most cases TDS is much less even less than 20 ppm. Kindly think of over this issue.
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?
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
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.
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.
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.
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.
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?
Thank you all for submitting different types of answers to my question. Recently there is a big issue on recommendation of RO water for drinking purpose. water below TDS 500 ppm is not suitable for drinking purpose as mentioned in various specifications. Towards this I want to mention that the specifications which mention a minium TDS value of 500 ppm for drinking water will be accepted assuming that water of that TDS should contain minerals such as useful salts of Na, Ca and Mg etc. which are really useful for every body. But we cann't be ensured that only useful salts will be present but not heavy metals such as Pb, As, Fe,Cr, Ni etc., fluoride and nitrate salts, chemical toxicity due to contamination of waste chemicals in soil and water discharged from various chemical industries, contamination of sewearage in water especially in city areas. All these contaminations can be removed from water using RO technique in most simpler way. Hence my suggestion is to use RO water after remineralisation with useful salts or RO with adjustable TDS facility. Such water is the best one for drinking purpose which can supply you a clean source of water with useful minerals added in controlled way. Another easy way to add trace quantity of rock salts to RO water for drinking purpose. Rock salt contains above 98 % NaCl and about 50 to 60 ions in trace level which are useful for human health.
World is facing unprecedented problem to safeguard 0.4 percent of potable water, which is eventually depleting day-by-day. From literature survey it has been observed that the refractive index (RI) of water changes with change in salinity or total dissolved solids (TDS). In this paper we have proposed an automatic system that can be used for real-t...