Ban RO systems if dissolved solids are less than 500 mg/l: NGT

The tribunal’s order came in response to a petition that said indiscriminate usage of ROs was leading to a huge wastage of water

By Banjot Kaur
Published: Tuesday 28 May 2019

The National Green Tribunal (NGT) on May 28, 2019, instructed the Union Ministry of Environment, Forest and Climate Change (MoEF & CC) to notify prohibiting the use of drinking water prepared through reverse osmosis (RO) systems in areas where the amount of total dissolved solids (TDS) was less than 500 milligram/litre (mg/l).

The order, which was uploaded on the NGT’s website on the evening of May 28, also asks the ministry to lay down a requirement for RO systems manufacturers that the recovery of treated water is at least 60 per cent and not more than 40 per cent should go as waste. Gradually, the recovery rate should be enhanced to 75 per cent.

The NGT gave the order upon hearing a petition filed by Sharad Tiwari, general secretary of a Delhi-based non-profit, ‘Friends’, who had pleaded that indiscriminate use of ROs was leading to huge wastage of water, which should alarm everybody, especially those in water-scarce areas. More than 163 million Indians do not have access to clean water, which is the highest in the world, the NGT order states.

“Now, the RO machine manufacturers would have to tweak their designs to meet the new parameters,” Tiwari told Down To Earth (DTE).

According to earlier standards issued by the Bureau of Industry Standards (BIS) in 2015, the water recovery by ROs had to be 20 per cent only. In fact, the order states that the association of RO system manufacturers had also admitted to the NGT that recovery was not more than 20 per cent.

The order came on the basis of a joint report submitted by the National Environmental Engineering Research Institute (Neeri), the Central Pollution Control Board (CPCB) and IIT-Delhi to the NGT early this week. The report had been prepared according to the NGT’s directions.

The order’s injunction that there was no need of RO systems in instances where the amount of TDS in water is less than 500 mg/l is based on the reasoning that RO is only meant to treat dissolved solids and according to BIS standards, drinking water is considered below par only if the TDS is above 500 mg/l.

It adds, “The RO manufacturers should provide labeling on the purifier specifying that the unit should be used if TDS is more than 500 mg/l.”

The joint report comes down heavily on what it calls the ‘misinformation campaign’ run by RO manufacturers.

“Application of RO in developed countries is limited to desalination, that is producing drinking water from high TDS containing seawater (which is salty). The growing use of this technology in treating low TDS water is the new normal in India. Although the application of RO is primarily ‘limited’ to removal of TDS, claimants of RO utility are promoting it to remove multiple pollutants,” the report says.

DTE checked the claims of two leading RO system manufacturers with one claiming the removal of “even dissolved impurities,” and the other claiming that “RO technology removes impurities” but does not specify the limitation.

“RO system companies have created a lot of fear and myths among the masses. This report and the order enlighten not just the policymakers but the common people as well. The government must notify these recommendations as early as possible to contain water wastage,” Tiwari said.

He added that the supply given by the Delhi Jal Board does not exceed more than 200 mg/l. Therefore, most Delhi homes actually do not require an RO system, he added.

But how would a common person know what TDS value the water supply s/he is getting, has? The committee recommends that whichever concerned local body or water board supplies domestic water should inform consumers about water source and quality, including the TDS concentration through the bills they send periodically. “This must be made mandatory,” the report reads.

The other problem that comes with the usage of RO technology is demineralisation of water. “Considering the fact that some scientific studies undertaken in other parts of the world warn about adverse health effects of dimenralised water, it will be pragmatic to not allow the use of low TDS water treated through RO (which leads to loss of precious minerals like Calcium and Magnesium),” the report states and adds that the RO manufactures should ensure 150 mg/l TDS in treated water.

The NGT order, while accepting this recommendation, went a step ahead and said the local water-supplying bodies should start awareness campaigns to let people know about the harmful effects of deminrealised water.

The report trashes claims by leading RO manufacturers in India about water having high arsenic and fluoride contamination being treatable by RO technology. “In areas with such contamination, appropriate contaminant specific technologies can be deployed so as to bring down concentration of these contaminants,” it states.

“This order makes it clear that RO is not the solution to all drinking-water related woes. One can use any other traditional filtration method to get pure drinking water when there is no need of RO,” Tiwari says.

And what does indiscriminate use of this technology give as by-product? The feed or the water that comes out as waste, has high quantity of minerals/contaminants and there is no clarity as to how it can be reused.

“RO reject water, with TDS concentration less than 2100 mg/l, can be used for cleaning vehicles, mopping floors, washing utensils, flushing and gardening. The risk of exposure due to usage of reject water is highly exaggerated and it can be utilised,” the order states quoting the report and adds that such water should be used for sprinkling in playing fields/cricket grounds rather than potable water.

However, it has a warning. “The RO reject can upset the land, surface water or sewerage system and the report suggests that the RO reject should be diluted before discharge.”

The NGT gives an important direction about disposal of used RO system cartridges once a consumer changes it. Usually, the service centre executive does not collect it and the customer has to dispose it. The order says the directions issued by MoEF & CC should also enforce the extended producers’ responsibility in this regard and thus fix the responsibility of disposal on the RO manufacturers.

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