While smart marketing strategies by RO water filter companies are drawing consumers by lakhs, the fact remains that this system wastes more water and also contaminates water sources

Homemaker Rajshri Jain has got used to the inevitability of collecting more waste water than filtered water from her reverse osmosis water purifier, called RO filter. For each litre of filtered water, her domestic filter dumps some three-four litres of waste water. Unlike most households using such filtration units, Ms. Jain has been collecting waste water in a tank for non-consumptive uses like floor cleaning and toilet flushing. 

Given the brackish nature of water supplied in her colony in upmarket Dwarka, be it from bore wells or from private water tankers, reverse osmosis is the only option at hand to ensure reasonable quality of potable water. With the quality of domestic water supply being highly unreliable, dependence on reverse osmosis is growing in leaps and bounds. No wonder, some six-seven lakh RO units get sold across the country each year.

Knowing well that over one lakh people die of water borne diseases annually in the country, the domestic water filter market has positioned itself to reach each and every household with several variants to suit diverse needs. Celebrity endorsements have pepped up the market that is expected to touch a whopping Rs 7,000 crore over the next couple of years, growing at more than 22 per cent each year with the RO system garnering a majority share.

Invented in 1949 by researchers from the universities of California and Florida, reverse osmosis technique was employed to produce fresh water from sea water. It applies pressure to force a solvent through a micro-sieve that retains dissolved salts after allowing pure water to pass through it to the other side. Since not all water moves through the sieve, what is left is often a highly concentrated solution. 

Imagine a colony of 400 households, and assume each household is using RO system for consuming 100 litres water per day, the daily wastage will be to the tune of 120,000 litres. That the waste water thus drained contaminates other sources rarely concern the urban consumers. Further, though the usual supply of water is largely usable, with minimum filtration, consumers succumb to the ‘better safe than sorry’ marketing bait of the filter water industry.

Since the RO purifiers are designed for treating even brackish water, these perform poorly in normal household conditions. Development professional Mithulina Chatterjee learnt it the hard way when she found that her RO filter was literally sequestering every molecule of salt from the supply and turning it bland in the process. “In their quest to mop the market, the RO filter companies hold back truth from the consumers,” says Ms. Chatterjee.

One could argue that wastage from RO filter should be admissible if one is trying to convert brackish water into drinking water. The trouble is that the challenge of re-using nearly 80 per cent of waste water released by RO filters for non-drinking applications rests with the user. This presents a serious concern since the technology per se wastes water. Should the municipal authorities continue to turn a blind eye to this emerging phenomenon?

In the absence of any regulatory restriction, manufacturers are encashing consumer sentiment by making tall claims like ‘turning drain water into pristine potable water’. And people are lapping it up to save on the cost of canned water. With groundwater being the major source of drinking water and the fact that groundwater in one-third of the country’s 600 districts is not fit for drinking due to high concentration of fluoride, iron and arsenic, RO filters get further hold on the market.

With increasing competition in the filter market, manufacturers are adopting smart marketing techniques to win consumer confidence. A leading company proposes to launch its patented product which claims zero water wastage. Priced at almost double the price of conventional RO filter, the system stores waste water in a separate ‘reject water tank’ for possible re-use for washing utensils, moping floor or gardening.

Since washing of the micro-sieve in the filter will reduce its life, the user will need to incur additional cost towards annual maintenance in the new system. Ms. Jain insists on going her way rather than paying additional costs towards replacing her existing RO filter. Unless the government comes up with centralised reverse osmosis systems covering housing clusters, the demand for water purifiers is bound to create a manmade water scarcity in the years ahead.

(The writer is with the Delhi-based The Ecological Foundation)