Reverse osmosis water filters unhealthy: WHO

Reverse osmosis (RO) water filters are not good for health according to a recent warning issued by the World Health Organisation (WHO).

RO filters not just kills the bacteria, but removes all salts and essential nutrients such as calcium and magnesium.

Experts have been warning about the rapid rise in the use of RO filters lately. Nevertheless, the government goes on installing RO plants in every nook and corner in the name of 'pure drinking water’.

M V Shashirekha, former chemist at the Department of Mines and Geology, says RO plants are good for highly contaminated groundwater with nitrate, flouride, etc. "From other sources though, RO filtered water can be harmful as it removes all essential nutrients," she adds.

“Reverse osmosis employs a partially permeable membrane to remove ions, unwanted molecules and larger particles from drinking water. This may reduce the concentration of particulate matter including suspended particles, bacteria and algae, reducing the concentration of a range of dissolved and particulate substances. Cauvery water may not require an RO filter. However, borewell water having high nitrates needs RO membrane filtering, as nitrates cannot be removed by boiling or other filters. The RO filter, meanwhile, removes all the essential minerals. To treat 10 litres of water, nine litres of water is drained, contaminating the groundwater. Those dependent on borewells must test the water quality and then zero in on the right filters,” Shashirekha elaborates.

A R Shivakumar, senior scientist, Karnataka State Council for Science and Technology, Indian Institute of Science, says the water filter lobby is so strong that they will never allow any study that would harm the business.

"RO plants are not calibrated keeping in mind the water source," he points out.

What WHO says

The presence of minimum/optimum concentration of calcium and magnesium in drinking water signify “energy content”. RO machines are very effective in cleaning water, but they remove calcium and magnesium, the elements responsible for producing energy. Therefore, long-term consumption of acidic water devoid of essential elements produced by RO filters is very unhealthy.