Reverse Osmosis (RO) Purifiers – Draft notification by Government

Science & Technology

Topic: General Studies 2:

Science and Technology- developments and their applications and effects in everyday life.  

About Reverse Osmosis

Reverse Osmosis is a technology that is used to remove a large majority of contaminants from water by pushing the water under pressure through a semi-permeable membrane.

Daily Current Affairs IAS | UPSC Prelims and Mains Exam – 10th February 2020

It works by using a high-pressure pump to increase the pressure on the salt side of the RO and force the water across the semi-permeable RO membrane, leaving around 95% to 99% of dissolved salts behind in the reject stream.
The amount of pressure required depends on the salt concentration of the feed water. Higher the concentration of salt, higher is the pressure required.

Reverse Osmosis is also used to produce water that is suitable for many industrial applications that require demineralized or deionized water

Issues with RO System

Wastage: RO systems now recover only 20 per cent of water while 80 per cent go waste
Can remove beneficial mineral: The process can cut the levels of calcium and magnesium, which are vital nutrients.
Membranes get clogged easily which happens when materials build up on the membrane and slow down the flow of water. Thus it requires constant replacement which increases operational costs
Not 100% purification capability: BIS standards clearly state that RO system is not recommended for treatment of raw water having Arsenic level above 0.1 mg/l and Fluoride level above 8.0 mg/l.

May 2019 NGT order had stated that

RO Purifiers should be prohibited where TDS (total dissolved solids) – which covers trace chemicals, certain viruses, bacteria and salts – in water was less than 500 miligram per litre (mg/l)

It had asked the government to redesign the RO system in a way that treated water would have a minimum 150 mg/l TDS concentration.
It also stressed on remineralisation to compensate for loss of minerals during RO treatment
It asked RO manufacturers to increase efficiency of systems to recover 60% of water inputs

Draft notification by the Union Environment Ministry (MoEFCC)

The notification issued on February 3, 2020 mentions that use of membrane-based water purification system (MWPS), mainly RO purifiers, shall be prohibited where drinking water complies with the Bureau of Indian Standards (BIS).

Enforcement will largely be the responsibility of CPCB and State Pollution Control Boards (SPCBs), taking water supply agencies on board to certify whether they provide potable drinking water in a particular area as per the prescribed BIS standard.

Concerns with the notification

The notification does not mention any limits prescribed in NGT order
The notification implies, these filters are only prohibited if the home gets water supply that conforms to BIS standards for Drinking Water.
Although several State and city water boards claim BIS standards, the water at homes falls short of the test parameters
The resort to prohibition (to restrict home filters) may cause consumer apprehension

Conclusion

The case for restricting people’s choices on the means they employ to ensure potable water is thus weak in view of above concern
Government’s primary aim should be to persuade authorities to upgrade and supply BIS-standard water at the consumer’s end and it should be done without additional costs.

Do You Know?

The BIS norms are voluntary for public agencies which supply piped water but are mandatory for bottled water producers.
The Composite Water Management Index (CWMI) of NITI Aayog says that 70% of water supply is contaminated.
India is ranked 120th among 122 countries in an NGO, WaterAid’s quality index.

Connecting the dots!

Nal Se Jal: Government’s mission to ensure piped drinking water to every rural Households by 2024