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IIT Madras Desalination Uses Solar Energy, Flat Collectors, and MED Technology to Transform Seawater into Drinking Water, Aiming for 10,000 Liters per Day, Pilot in Kanyakumari, Compact Prototype on Campus, and Possible Applications in Islands, Condominiums, Academic Campuses, and Coastal Regions of India in the Future.
The compact solar desalination developed by researchers at IIT Madras gained prominence on June 4, 2025, following the advancement of a system capable of producing drinking water from seawater using solar heat. The project aims for a production of 10,000 liters per day in a plant based on thermal technology.
According to The Times of India newspaper, the pilot was conducted in Kanyakumari, at the southern tip of India, in partnership with the National Institute of Ocean Technology and supported by the country’s Ministry of Earth Sciences. The proposal is to take the technology out of the laboratory and bring it closer to locations that need fresh water without relying solely on traditional supply networks.
Solar Desalination Uses Sun’s Heat Instead of Conventional Electricity
The system developed by IIT Madras uses flat solar collectors to heat seawater. This water reaches about 75Ā°C and, within the process, is transformed into vapor under vacuum.
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The logic is to use the sun’s thermal energy as the main driver of desalination. Instead of relying on an electricity-intensive solution, the plant harnesses solar heat to initiate the separation between water and salt.
The process employed is called multi-effect distillation, known by the acronym MED. In this model, evaporation occurs in successive stages, making better use of the available heat.
The water is not simply boiled all at once. It goes through a controlled sequence, in which the vapor condenses and generates fresh water at different stages of the system.
Four Evaporation Chambers Transform Seawater into Drinking Water
The plant uses four evaporation chambers. The steam generated in the process passes through these chambers and condenses into clean water at each stage, increasing thermal efficiency.
An ejector maintains the vacuum around 100 millibar, removing air from the system. This condition allows the water to boil at lower temperatures, which reduces the heat requirement and improves the process efficiency.
According to the researchers, the plant produces about 300 liters of fresh water per hour between 10 a.m. and 3 p.m., the period of greatest solar availability. The water generated had a salt content of only 1 part per million.
This result is significant because it shows that solar desalination can deliver low-salinity water using a thermal and compact structure. For coastal regions, islands, and places with abundant sun, the model can have strategic applications.
Compact prototype was built on the IIT Madras campus
Besides the pilot plant in Kanyakumari, the team developed a compact version on the IIT Madras campus. This prototype measures 2 m by 2 m and can produce 100 liters of fresh water per hour.
The compact version was optimized by Thilagan K., a researcher at the refrigeration and air-conditioning laboratory at IIT Madras. He replaced a bulky shell and tube heat exchanger with a thin plate design, reducing space and energy consumption.
Before installation, the researchers used simulation tools to model and test the complete system. Components such as the flash chamber, multi-stage evaporator, condenser, ejector, and solar collectors were analyzed individually.
This care shows that the technology was not assembled just by practical trial. The team validated parts of the system before integrating everything into a smaller solution, more suitable for decentralized use.
System can operate at night with thermal storage
One of the challenges of solar energy is intermittency. The system relies on the sun’s heat, but the researchers claim it can also operate at night if combined with a thermal storage solution.
In this case, the heat produced during the day would be retained for later use. This would allow the desalination process to extend beyond the hours of highest solar radiation.
The possibility is important for places that need water continuously. Producing only during the day may be sufficient for some uses, but community or institutional applications may require greater regularity.
Thermal storage could be the piece that transforms a daytime solar solution into a more stable source of drinking water. Still, the feasibility will depend on cost, scale, and maintenance.
Researchers target islands, condominiums, and academic campuses
Professor Advaith Sankar, from the mechanical engineering department at IIT Madras, stated that the technology can be cost-effective, including operational and maintenance costs, when scaled up.
He also highlighted that the system can work well in residential colonies and academic campuses. These are environments where water demand is concentrated, predictable, and can justify having their own plant.
For IIT Madras, solar-powered desalination can gain ground in regions where drinking water is a constant challenge. The pilot in Kanyakumari serves as a reference to test if the technology can be replicated on islands, condominiums, campuses, and coastal areas.
The team is also in talks with the Indian Navy to replicate the system in island regions. Islands often face greater supply challenges as they depend on transportation, rain, limited aquifers, or local treatment structures.
In this context, compact solar desalination can offer a more autonomous alternative. The difference lies in using an abundant source in many coastal regions: the sun.
Greywater also enters the reuse plan
Besides seawater, the team is working on developing a greywater treatment unit. The idea is to recycle wastewater from kitchens for uses such as gardening and toilet flushing.
This front expands the scope of the project. Instead of only thinking about producing drinking water, the researchers are also evaluating how to reduce waste within communities, buildings, or institutions.
The combination of desalination and water reuse can be especially useful in places where supply is expensive or unstable. Producing fresh water and reusing part of the used water creates a more efficient cycle.
Sanitary safety and correct separation of uses will be fundamental. Water for drinking, water for gardens, and water for flushing require different standards, and each application needs to be treated with technical rigor.
India tests compact solution for a global problem
A India is not alone in the search for alternatives for drinking water. Coastal regions in various countries face increasing pressure on rivers, aquifers, and reservoirs, while urban and industrial populations demand more supply.
The IIT Madras technology draws attention because it tries to unite three factors: solar energy, compact design, and decentralized production. The goal of 10,000 liters per day places the system at an intermediate scale, above simple domestic solutions and below mega desalination projects.
The proposal still needs to advance in patenting, replication, and validation in different environments. Costs, maintenance, input water quality, and thermal storage will be decisive points to determine where the model can work best.
In the end, Indian solar desalination shows how the race for drinking water also involves smaller, modular systems adapted to specific communities.
Do you think compact solar-powered solutions can help islands, condominiums, and campuses, or will large plants still be the main way to tackle water scarcity? Share your opinion
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