The demand for a reverse osmosis water filter device has been growing in my household. ‘Has our existing water filter stopped being friendly?’ has been my consistent query. ‘It is time we got a new one’ has been the standard response. Considered to be one of that generation to whom the ‘utility’ of a product carries a lot of meaning, listing the virtues of new technology has often been used as a technique to floor my persistence. This time, however, I decided not to give up easily.
Far from comparing designs and checking price levels, I set out to find out from actual users their experience of using RO filters. What got me into a serious investigation of the reverse osmosis system was a simple observation from a neighbour’s wife who told me that for each litre of filtered water, her domestic RO filter dumped three to four litres as waste water. Isn’t it a significant ratio given that potable water is becoming scarce?
With a background of some sorts in engineering, I sought to get to the root of the problem. What I learnt is both revealing as well as shocking to an extent. Shocking because threat perceptions related to water-borne diseases have led many people to put money into water purifying systems. And revealing because the hidden cost of wasting water by blindly adopting a technology has gone unnoticed.
Public water supply continues to evoke little confidence in terms of quality. No wonder, the domestic water filter market has come knocking on every door. Celebrity endorsements have pepped up the market that is expected to grow to a high of Rs. 7,000 crore over the next couple of years. The growth has been at a rate of more than 22 per cent a year. The RO systems represent a major share in this.
The market is known to exploit public sentiment, often with little regard to ethics and morality. That is how the market has shaped and grown. The question that comes to mind is whether the technology is so designed as to waste water, or is the user at fault in its application? I would imagine it is both: the markets for not letting the user know the inherent weakness of the technology, and the consumer for being cosy with his or her ignorance.
What is the inherent nature of the reverse osmosis system? It was invented in 1949 by researchers from the universities of California and Florida, where the technique was employed to produce potable water from sea water. Pressure is applied to force sea water through a micro-sieve, which retains the dissolved salts and allows pure water to pass through it to the other side. The water left behind is often a highly concentrated solution.
Further interaction with friends and colleagues led me to conclude that wherever piped water or tanker supply is brackish, the use of a reverse osmosis filter alone can rid water of excess salts. However, in areas where the supplied water is not loaded with dissolved salts, ordinary filters that primarily use activated charcoal to remove impurities should suffice.
If RO water filters are used in cases where they should not be used, it acts like a double-edged sword. Not only does water get wasted, though not as much as in the case of brackish water, but also the RO filter sequesters every molecule of salt from the water and turns it bland in the process. Consuming such depleted water can be hazardous to health, especially for toddlers and growing children.
Since water supplied in the colony where we live is not brackish, it may not do any good to us if we opt for an RO filter. If every household in the 250-households colony were to use RO filters, consuming 100 litres a day, the cumulative daily wastage could be to the tune of no less than 25,000 litres, assuming that for each litre that is filtered through RO at least two litres get wasted.
The story does not end there. The concentrated waste water thus drained adds to contamination of the drainage system. We can easily ignore this, but can we be oblivious to the fact that fresh water is getting scarcer by the day? With increase in population on the one hand and wastage of water on the other, the annual per capita availability has declined to a low of 1,500 cubic metres. This puts India among countries that are ‘water stressed’.
While we have finally taken a decision not to go for an RO filter at home, my advice to others who have no option but to use an RO filter is to use the discarded water to wash utensils or mop the floor. A small tank could be attached to the RO filter to collect such water for alternative use. Till such time the RO technology stops generating waste water, we have little option but to use a technology that wastes water. Consumer education is critical to the adoption of any technology.
sudhirendarsharma@gmail.com
