Are RO purifiers necessary?

By: Staff Reporter
English Free Article Science Bytes

New Delhi, February 15 (G’nY News Service): It is common perception today that the water provided by urban local bodies is not up to the mark and that we need water purifiers. With this in mind, most of us demand the best of purifiers that money can buy. But how good are these technologies? Do they help purify the water we drink, and keep us safe enough?

According to the Bureau of Indian standards, Water with TDS levels 500 and below without conventional treatment but after disinfection is safe for drinking. (

In Delhi, the water supplied by Delhi Jal Board, and studied by Consumer Voice, in Nov. 2015 was found to have acceptable TDS levels at every place surveyed.


TDS levels in drinking water supplied by BJB

RO 1


There are places where the water being provided by authorities is not up to the mark, or the groundwater has high levels of TDS, as can be ascertained by a July 2008 study from the Indian Environmental Portal (, necessitating the use of RO. However, using RO in areas where the water provided by DJB is being used further lowers the level of TDS.

TDS levels in Delhi Groundwater

RO 2

The RO purifier uses the Reverse Osmosis (RO) technique in which a high pressure pump is used to increase the pressure on the salt side of the RO and force the water across the semi-permeable RO membrane, leaving almost all (95% to 99%) of dissolved salts behind in the reject stream.

“The TDS of seawater varies between 30,000- 40,000. The RO purifier helps lower it to 200-300 mg/l (TDS recommended for drinking water). Whereas when used for household purposes, it lowers the TDS levels to 20-30 mg/l, which is not recommended,” says Dr CK Jain of the National Institute of Hydrology.

According to Dr Jain, RO doesn’t remove any bacteria or virus from the water and hence, water purified by RO is still capable of making you ill. “To remove harmful impurities like bacteria, boiling or the UV technique should be used. In fact, RO is completely useless,”

When Pentair, a company dealing in water purifiers, was asked by a GnY correspondent on why should one use a water purifier when UV or boiling can help achieve better bacteria removal , the Pentair representative asserted, , “without RO, water will not be pure”. He also proudly mentioned that the TDS of water is reduced by RO to 50-100 ppm.

The cost of an RO purifier varies anywhere between Rs 2,000 upto Rs 40,000 in the market whereas the cost of UV purifiers goes up to 26,000. The cost of RO+ UV based purifiers is around Rs 7,000-15,000. It is clear, thus, why a useless technique like RO is being promoted to such an extent.

Alongside the high prices, the regular maintenance of RO filters poses a major problem. “RO filters need to be serviced every four months leading to an added cost of Rs 1400 a year,” says Ms. Geetanjali of RO Care. When people don’t bother to maintain them, it leads to contamination of the tank due to bacteria getting trapped in the filter, causing a health risk.

As Dr. CK Jain says, “RO is totally useless and is not recommended for household purposes. It is only a status symbol today.”

In short, ‘Dunia Ka Sabse Shudh Paani’(Kent),’ As Safe As Boiled Water (Purit)’, are taglines that deceive people into shelling out their hard- earned money for technologies that are not just useless for them but possible hazards.

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