Explanation:

The Union Environment Ministry has published a draft notification that effectively prohibits users from installing MWPS [Membrane-based Water Purification System], mainly reverse osmosis, in their homes if the water has been sourced from a supply that meets the BIS drinking water norms. Installation or use of MWPS shall be prohibited, at the point of use or at the point of entry for purification of supplied water which is subjected to conventional flocculation, filtration and disinfection process or is from any sources which are in compliance with acceptable limit for drinking water prescribed by Bureau of Indian Standard 10500:2012. The proposed regulation is not the final word and the Ministry will await comments from the public for 30 days, after which it may incorporate the changes before it becomes a law. The Ministry has issued this order to comply with an order of the National Green Tribunal (NGT), which has prohibited the use of reverse osmosis (RO) purifiers in places where total dissolved solids (TDS) in the supplied water are below 500 mg per litre. The NGT had ordered a ban on RO filters on the grounds that they wasted water and that, in the process of removing salts, they often deprived drinking water of essential salts. Current Bureau of Indian Standards’ (BIS) regulations consider 500 mg/litre—1,200 mg/l of total dissolved solids, which consists of salts and some organic matter, as acceptable though there is no lower limit. Hence both statements are correct.