Water

Centre's new draft for RO systems not what NGT asked for

Green Bench sought ban on ROs for water with TDS below 500 mg/l

 
By Shagun Kapil
Last Updated: Thursday 06 February 2020
Drinking water. Photo: libreshot.com

The Union government's new draft notification on regulating reverse osmosis (RO) purifiers contradict directions by the National Green Tribunal (NGT), which had sought such a notification to curb indiscriminate use of ROs.

The May 2019 NGT order, among other things, had clearly stated that ROs should be prohibited where TDS (total dissolved solids) in water was less than 500 miligram per litre (mg/l). It had asked the government to redesign the RO system in a way that treated water would have a minimum 150 mg/l TDS concentration. It also stressed on remineralisation to compensate for loss of minerals during RO treatment. 

The draft notification issued February 3, 2020 by the Union Ministry of Environment and Forests and Climate Change (MoEFCC), however, does not mention such limits. 

Instead it only mentioned that use of membrane-based water purification system (MWPS), mainly RO purifiers, shall be prohibited where drinking water complies with the Bureau of Indian Standards (BIS).

It said:

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 - Drinking Water Specification.

Whether or not a particular sample of water is BIS-compliant depends on several parameters, not just TDS. Whereas, the RO technology is limited to the removal of excess TDS and won’t work in cleaning other impurities or metals in water. 

The expert committee report had said: “BIS standards clearly state that RO system is not recommended for treatment of raw water having Arsenic level above 0.1 mg/l and Fluoride level above 8.0 mg/l.”

Suppose a household receives water with TDS below 500 mg/l but has other elements (eg, nitrates, sulphates, fluorides, etc) above the acceptable limit of BIS, that water will still not comply with the specification. The household, however, would not require an RO system to treat it as TDS was already within limits. It would not be effective in treating other impurities.  

In the absence of any regulation, however, RO manufacturers claim to treat hazardous chemicals other than TDS. This misleads consumers.

This was the moot point of the NGT order and of the expert committee report on which it was based — to stop the indiscriminate use of RO technology where not required. 

Court directions were very clear but the draft notification has diluted them. BIS specifications include several parameters and water could be tested based on all of them and not just TDS,” said Sharad Tiwari, general secretary of NGO Friends, who first filed the petition in the green tribunal against wastage of water due to ROs. 

“Based on this notification, there remains no meaning of the NGT order and we are back to square one. We will challenge it in the court again,” he added.

The notification was also silent on the minimum TDS value. According to the NGT order:

The Expert Committee Report last examined the issue of deficiencies caused on account of RO system removing important minerals such as calcium, magnesium, etc, which adversely affects the health of consumers of demineralised water. This calls for prohibiting and regulating consumption and use of low TDS water by requiring manufacturers to maintain minimum TDS concentration to 150 mg/l or the minimum levels of calcium and magnesium.

However, the draft notification only mentions BIS-compliance.  The BIS does not have any minimum limit for TDS in treated water and was asked by the NGT to work on it. 

The draft though abided by the NGT directions to RO manufacturers to increase efficiency of systems to recover 60 per cent of water inputs. RO systems now recover only 20 per cent of water while 80 per cent go waste.

Once the notification is finalised, BIS will modify standards for RO purifiers (IS16240), a BIS official said. Licensing for manufacturing ROs and BIS certification will be mandatory after that, the official added.

Currently, it is a voluntary process, opted for by only one company so far. 

The ministry sought comments from the public within 30 days, after which a final notification will be released.

Ironically, the committee that recommended the draft notification comprised representatives from RO manufacturing associations along with representatives from the BIS, National Environmental Engineering Research Institute and the Central Pollution Control Board, among others. 

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