Reverse Osmosis (RO) is a method used in water treatment. It was developed to remove salt from seawater and remains the leading technology for that purpose worldwide. Many rural and urban communities in India, however, have turned to RO technology as a means to purify drinking water from fresh water sources, including pre-treated municipal water. This widespread use is a result of aggressive marketing by businesses, particularly as a household product in urban sectors in India. Even armed forces have not been immune to the influence of advertisements and propaganda driven by companies. As a result, there has been a surge in private vendors who are permitted to operate RO plants in garrison or antonments, to supply drinking water as an alternate source. [1] Community level RO systems continue to be installed in rural areas by various NGOs (Non-Governmental Organizations) through state-sponsored programs.[2] It is important to increase awareness about the damage that the irresponsible use of RO technology can cause, both to the environment and health.

So why is RO not recommended to purify fresh water?

Demineralisation of Water

First and foremost, consumers need to understand that the process of reverse osmosis results in demineralised water, i.e. almost free of naturally dissolved minerals. The process is far from efficient, resulting in the loss of more than 80% of the treated water. Further, Demineralised water is highly aggressive and leaches out metals and other materials from pipes and associated plumbing parts.3 In some cases, the processed water is remineralised i.e. a few minerals are added to the water in an additional step. Regardless, the effects of drinking demineralised water are generally not considered because such water is not found in nature, except possibly for rainwater and naturally formed ice.[3] While the high risks of drinking contaminated water or consuming excess ions are well-known, the risks from long-term demineralised water are less recognised.