NEW DELHI: Acting on the National Green Tribunal (NGT) order asking the Centre to prohibit use of reverse osmosis (RO) purifiers where total dissolved solids (TDS) in water are below 500 milligrams per litre, the environment ministry on Monday issued a draft notification seeking users’ views before banning RO purifiers in areas which get potable drinking water.

The ministry’s draft, however, was silent on the TDS limit and preferred to go by the “acceptable limit for drinking water prescribed by the Bureau of Indian Standard (BIS)” which is aligned with international specifications. It also said water from RO purification system for domestic use would be “used only for drinking purpose”.

Once the rules are finalised, RO machine manufacturers will have to tweak their designs to meet the new parameters so that the system does not discharge water beyond the prescribed limit during the purification process.

As far as monitoring and enforcement are concerned, the draft left it for BIS to develop a system to monitor, assess and certify in consultation with the Central Pollution Control Board (CPCB) within six months of final notification.

Enforcement will largely be the responsibility of CPCB and State Pollution Control Boards (SPCBs), taking water supply agencies on board to certify whether they provide potable drinking water in a particular area as per the prescribed BIS standard.

Through this draft, the ministry sought public comments which may be sent to joint secretary Jigmet Takpa within 30 days. Final notification on banning RO purifiers and parameters on design of such machines will be issued after examining the views of all stakeholders, including manufacturers.

The draft also listed dos and don’ts for manufacturers and importers, keeping in view water conservation regulations in the country. The draft said any violation would be brought to the notice of SPCBs or the CPCB or the environment ministry. “The CPCB will be the nodal agency for implementation of these rules,” it added.

Besides potability of water, the draft also looked at water use efficiency of RO systems and regulations pertaining to discarded elements in the treatment system where polymer-based membrane is used and discarded at the end of its life.

It said discarded elements will not be disposed of in any manner other than the applicable provisions of the Plastic Waste Management Rules, 2016.

The NGT had in May last year also asked the ministry to lay down a requirement for RO systems manufacturers so that the recovery of treated water was at least 60%. Its order had come on a petition filed by Delhi-based NGO ‘Friends’, which had pleaded that indiscriminate use of RO systems was leading to huge wastage of water.

