Treating water

The National Green Tribunal (NGT) has set the year-end as the deadline for the environment ministry to bar the use of reverse osmosis (RO) water purifiers in places where the available water conforms to the prescribed quality norm of dissolved solids content of below 500 mg per litre. The move aims chiefly at preventing the wastage of water and several useful minerals and essential salts that are lost during RO treatment. Many households routinely use RO water purifiers to reprocess the piped water supplied by civic bodies after cleansing it through the standard methods involving flocculation, filtration, and disinfection. In many of these cases, especially where the load of the dissolved solids is less than the 500 mg threshold, RO filtration is neither required nor good for health. It leads virtually to total demineralisation of water by needlessly eliminating its inherent micronutrients, thereby, making it unhealthy and tasteless. In these cases, the commonly available UV (ultraviolet) and UF (ultra-filtration) systems of water refinement are deemed good enough. The RO system is needed essentially to make sea water, or hard and saline underground water potable. The NGT has now specifically asked the environment ministry to sensitise the public about the ill-effects of demineralised water. 

The RO industry, as could be expected, has continued to sulk over this matter. While formalising the new norms for the use of the RO systems, the government should consider some suggestions from the industry. One of the key arguments, which may be hard to refute, is that even the water subjected to conventional cleansing treatment can have certain organic and inorganic residues and traces of heavy metals to make it unfit to drink. This has often been noticed in mega cities and industrial towns and RO purification can take care of this menace. 

But indiscriminate use of RO technology is inadvisable from the environmental angle as well. It results in the wastage of 70-80 per cent water. A water-stressed country like India can ill-afford to squander this scarce, even if renewable, natural resource. The NGT has, therefore, directed the government to make it mandatory to recover at least 60 per cent water from RO units. This would require the industry to make fresh investment in technology upgrade to build new and more efficient RO models capable of cutting down water wastage. The issue of regulating the use of RO equipment has a chequered, though short, history. The order to this effect was originally issued by the NGT in May 2019. But it had to be re-issued a couple of times, with fresh target dates, because of the environment ministry’s procrastination in implementing it. The decisive action began only after the Supreme Court turned down the RO industry’s plea to intervene in the matter and the NGT set the final deadline. As part of the requisite spadework to enforce this injunction, the government came up with the draft of the notification for stakeholders’ comments in the beginning of February. However, the follow-up action was disrupted due to the Covid-19 outbreak. The process may finally get going now.