Last Updated on September 29, 2025 11:22 pm by BIZNAMA NEWS
R. Suryamurthy
A research team at the Indian Institute of Science (IISc) has developed a siphon-powered thermal desalination system that could make seawater purification faster and more affordable. The breakthrough, published in the journal Desalination and backed by the Department of Science and Technology, promises to overcome two long-standing obstacles in solar desalination: salt crust buildup and the limited reach of capillary-driven systems.
At the heart of the system is a composite siphon made of fabric and grooved metal that continuously draws seawater from a reservoir. Gravity ensures the flow remains uninterrupted, flushing out salt crystals before they accumulate. The water evaporates on a heated surface and condenses across a narrow two-millimetre air gap, producing over six litres of fresh water per square metre per hour under sunlight—several times more than conventional solar stills.
The team says the device can also handle brine concentrations of up to 20 per cent without clogging, a significant advance in treating saline waste. Made from low-cost materials such as aluminium sheets and fabric, the desalination unit can run on either solar energy or industrial waste heat.
“This is about scalability, salt resistance and simplicity,” the researchers said, adding that the technology could be deployed in water-stressed coastal villages, island communities and disaster-hit regions.
But experts caution that lab-scale success does not always translate into real-world impact.
“Efficiency numbers from controlled experiments often look impressive, but scaling up to a community or municipal level involves challenges of durability, maintenance and cost recovery,” said an independent water technology consultant based in Chennai. “Materials may degrade under long-term exposure to sunlight, salt and humidity.”
Others point to energy trade-offs. “Even with solar input, desalination requires substantial heat, and maintaining consistent performance in cloudy or variable climates could be difficult,” said a researcher at a global water policy think tank.
There are also questions about affordability. While the unit relies on relatively cheap components, the cost of mass manufacturing, distribution and after-sales support will determine whether it is truly viable for rural and low-income communities. “A one-off prototype in a lab is not the same as a system that households can buy, maintain and repair at scale,” said an official from a non-profit working on safe water access in South Asia.
Globally, desalination remains energy-intensive, with most large-scale plants powered by fossil fuels. India’s push toward decentralised, renewable-driven systems could help bridge access gaps, but experts stress that technologies must be tested rigorously under field conditions.
Despite these caveats, the IISc innovation underscores India’s growing role in developing low-cost water technologies. If it survives the leap from laboratory to local deployment, the siphon desalination system could mark an important step in making the oceans a dependable source of drinking water for millions.
