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May 10, 2024

Most Of India Probably Doesn't Need An RO Water Purifier At Home, Say Scientists; Here Is Why

RO systems, popularly known as water purifiers have now an almost indispensable item in our kitchens, just like refrigerators and mixers. From big cities to small towns and villages, people trust

RO systems, popularly known as water purifiers have now an almost indispensable item in our kitchens, just like refrigerators and mixers.

From big cities to small towns and villages, people trust these reverse osmosis systems to provide them with pure and healthy water for their families, because that is what the advertisements and the sales representatives tell us.

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And to be fair, these RO water purifiers do what they promise, most of the time. But at what cost? An average RO purifier ends up wasting around three times the amount of water it purifies.

In other words, for every one litre of purified water, you get from the RO machines, three litres of water are wasted.

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This along with the fact that the water consumed by most Indians is well within the safety standards of the WHO should tell you that, you probably rethink bout having a a water purifier, at least not an expensive RO system.

Dr. Sambuddha Misra, an Assistant Professor at the Indian Institute of Science Bangalore (IISc) who has studied this extensively believes in most cases, the water you get doesn't have to go through an RO system.

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"In most cases what we have found is that the metal concentration in the water is much lower than what the WHO regulates as good drinking water. We are not saying that the bacterial load is low, but to purify that, you don't need an RO. Because for every ten litres of water that goes through these RO systems, you get three litres of good water and the remaining seven go out with more metal concentration through the sewage lines or to the ground which will end up adding more pollution to the groundwater," Dr. Misra explained.

Dr Sambuddha Misra

In 2021-22 Dr. Mishra and his team conducted extensive studies in Haldia, West Bengal, where they found that the metal concentration including lead, was much lower than what was originally thought.

According to him the current idea of putting all the water through an RO system is not sustainable and will do more harm in the long run. He said localised solutions should be implemented to meet the requirement of specific areas.

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Along with the promise of clean water, what the RO systems do is remove all the natural minerals and ions from it.

Dr. Indra Sekhar Sen, an Associate Professor at IIT Kanpur compared the blanket use of RO to using a cannon to kill an ant.

"What the RO does is remove all the total dissolved solids from the water, making it 'too pure' to the point it is not good for drinking. Since ROs are still relatively new, we don't know the long-term health effects of drinking bland water, from which all its natural minerals are removed," Dr. Sen said.

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According to the Bureau of Indian Standards (BIS), the limit of TDS levels in drinking water is 500 ppm. But it doesn't mean that anything above this level is unsafe.

"The WHO says 300 ppm is the limit, but it doesn't say that if it is above 300 ppm, it will have health effects. Even our BIS says up to 2000 ppm, is acceptable for drinking where other water sources are not available. But the RO industry can't tell you that," Dr. Sen said.

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The RO industry's marketing gimmicks have not gone unnoticed and in 2019 the National Green Tribunal (NGT) directed the Ministry of Environment, Forest and Climate Change (MoEF&CC) to issue "appropriate notification prohibiting use of RO where TDS in water is less than 500 mg/l and wherever RO is permitted, a requirement is laid down for recovery of water be more than 60%.

Further provision be laid down for recovery of water upto 75% and use of such RO reject water for purposes such as utensil washing, flushing, gardening, cleaning of vehicles and floor mopping.

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Faced with pushback over water wastage and removing TDS, the RO manufacturers have been marketing their new products claiming that they have 'added minerals'.

"First with RO, they remove all the ions, then they realised that the water is bland. Now they are adding mineral enhancers, which is making the RO system more expensive. Also to address the issue of water wastage, what they are doing is to put the wastewater back into the inlet pipe, so that there is some recycling," Dr. Sen said.

In Haldia, where Dr. Misra's team carried out the water quality assessment, they also launched a pilot project where they are creating awareness among residents to tell them what kind of water purification they should have at home if at all they need one, based on the source of their water supply.

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"What we have seen is that in most places, except some areas where there were petrochemical industries, the water had some zinc pollution, all other waters were directly drinkable," Dr. Mishra said.

So, if not RO what should we do to purify our drinking water and be confident that it is safe?

According to Dr. Sen, the simplest and most cost-effective way is to boil it.

"Removing bacterial load is very easy, you just have to boil it, and all the bacteria will die. The problem comes with the ions because they are very small in size and they cannot be removed through normal filtration processes," he said.

Dr. Sen's team has been working on a cheaper, no-waste solution to purify water in collaboration with MIT in the US. It is called CLEAR which stands for - Cleansing, Light, Easy, Affordable, and Reusable.

Dr. Indra Sekhar Sen

According to him, CLEAR is a bottle that has a sorbent tailored to remove contaminants from the specific water and not all ions, like the RO.

All the user needs to do is fill the bottle with contaminated water, and the sorbent will take up the target contaminants and pure water will come out.

Currently, the bottles are of one litre capacity, but the size can be customised to meet household needs.

"While we have this low-cost, zero-wastage technology, the larger question is do we really need even this? What our data and other studies have found is that around 70 per cent of the water is safe to consume directly, or needs some UV-filtration and definitely not RO," Dr. Sen said.

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