A UK teenager’s solar powered water purification system that works in cloudy conditions won the prestigious 2025 Stockholm Junior Water Prize People’s Choice Award.
A UK student has won the People’s Choice Award at the 2025 Stockholm Junior Water Prize for creating a solar powered water purification system that works even on cloudy days. Divyasri Kothapalli’s innovation uses concentrated sunlight to purify contaminated water without electricity, making it ideal for communities without reliable power access.
The award ceremony took place during World Water Week in Stockholm, where over 30 countries competed in the world’s most prestigious youth water research competition. Thousands of students submitted entries, with global voters selecting Kothapalli’s solar powered water purification system as their favorite among the finalists.
The Stockholm Junior Water Prize has recognized outstanding young water innovators since 1997. The Stockholm International Water Institute founded the competition to encourage youth participation in solving global water challenges. Crown Princess Victoria of Sweden serves as the competition’s patron, highlighting its international importance.
Kothapalli’s system addresses a critical global need. Nearly 2 billion people worldwide lack access to safely managed drinking water at home, according to the World Health Organization. Traditional water purification methods often require electricity or expensive equipment, putting them out of reach for many communities.
The innovation centers on a Fresnel lens, a flat lens with concentric rings that focuses sunlight into intense heat. This concentrated solar energy boils contaminated water in a repurposed metal container. The steam then travels through food-grade silicone tubing, where it condenses back into clean, distilled water.
What makes this solar powered water purification system unique is its ability to function in less-than-ideal weather conditions. While most solar devices struggle on overcast days, Kothapalli’s design can still purify water in cloudy climates like the UK. The concentrated sunlight effect remains strong enough to reach boiling temperatures even when direct sunshine is limited.
The materials needed are both affordable and widely available. Communities can source metal containers locally and purchase Fresnel lenses and silicone tubing at relatively low costs. This accessibility makes the technology practical for widespread adoption in rural areas, disaster zones, or regions with unreliable power grids.
Kothapalli tested her system extensively under various conditions. She measured water purification rates across different sunlight intensities, tested multiple contamination levels, and monitored performance during changing weather patterns. The results showed consistent water production even during overcast UK conditions, with reliable distillation rates that could meet household needs.
The system produces zero carbon emissions during operation, relying entirely on renewable solar energy. Unlike some water treatment methods that create chemical byproducts or require fossil fuel-powered equipment, this innovation leaves no environmental footprint beyond its initial manufacturing.
The environmental benefits extend beyond clean energy use. Climate change increasingly threatens groundwater supplies through droughts, floods, and pollution. Solar powered water purification systems can help communities maintain water security when traditional sources become compromised.
Kothapalli’s motivation stems from personal experiences with water access challenges and a commitment to climate resilience. Her work received support from scientific organizations, educational institutions, and water experts who provided mentorship throughout the development process.
When compared to existing water purification solutions available to off-grid communities, Kothapalli’s innovation offers significant advantages. Ceramic water filters, while effective against bacteria, cannot remove dissolved chemicals or salts that contaminate many water sources. These filters also require regular replacement and may cost $20-50 per unit.
Ultraviolet sterilizers effectively kill pathogens but need battery power or electricity to operate their UV lamps. Battery-powered units cost $100-300 and require ongoing battery replacements. They also cannot remove chemical contaminants or improve water taste and clarity.
Traditional water boiling requires substantial fuel supplies, whether wood, charcoal, or propane. In many regions, fuel costs make daily water boiling economically unfeasible. A family might spend $2-5 daily on fuel just for water purification, making it unaffordable for low-income households.
Chemical water treatment tablets offer portability but cost roughly $0.50-1.00 per day for a family’s water needs. Long-term use becomes expensive, and the tablets cannot address all types of contamination. Some people also dislike the taste that chemical treatments leave behind.
In contrast, Kothapalli’s solar powered water purification system requires no ongoing fuel costs, battery replacements, or consumable supplies after the initial setup. The one-time investment of approximately $50-100 for materials can provide years of clean water production without additional expenses.
The award ceremony attracted global water experts, representatives from sponsor companies like Xylem Inc., and a worldwide streaming audience. The competition features multiple award categories, including the main prize, Diploma of Excellence, and the People’s Choice Award based on international voting.
Jury members praised Kothapalli’s project for combining innovation with practical accessibility. The solar powered water purification system’s climate impact potential and low-barrier implementation impressed sustainability leaders and engineering experts who evaluated the submissions.
Other winning entries demonstrated the diversity of youth approaches to water challenges. Projects included flood warning systems for vulnerable communities, advanced contaminant removal technologies, and innovative water retention devices for drought-prone regions.
The Stockholm International Water Institute emphasizes that competitions like this play a crucial role in developing future water leaders. Young innovators often bring fresh perspectives to complex problems, developing solutions that established experts might overlook.
Current development plans include adapting the solar powered water purification system for different climate zones, from arid deserts to tropical regions. Kothapalli is exploring partnerships with non-governmental organizations and government agencies to pilot the technology in communities facing water security challenges.
The innovation shows promise for local fabrication, meaning communities could potentially build their own systems using readily available materials. Open licensing could make the design freely available, allowing widespread adoption without patent restrictions.
International interest has grown since the award announcement. Multiple countries are considering pilot studies to test the system’s effectiveness in their specific environmental conditions and community contexts.
The success of this solar powered water purification system reflects a broader trend toward climate-smart water technologies. As traditional water sources face increasing pressure from environmental changes, innovative solutions become essential for maintaining global water security.
See also: Atmospheric Water Harvesting Technology: Thai Students Win Global Prize for Innovation
The Stockholm Junior Water Prize continues to inspire young people worldwide to tackle water challenges through science and technology. These youth-led innovations often become the foundation for larger-scale solutions that benefit millions of people.
Kothapalli’s next steps include further research, system refinement, and expanded testing in diverse environments. She plans to engage with communities that could benefit from the technology while continuing to develop improvements that increase efficiency and reduce costs.
The award recognizes not just individual achievement but the potential for youth innovation to drive meaningful change in global water access. As climate challenges intensify, solutions like solar powered water purification systems may become increasingly vital for communities worldwide.
Sounds like Kothapalli’s research could have the most impact of these by improving and saving hundreds of millions of lives. She’s following the footsteps of Victor Papanek’s Design for the Real World. One small example is Gaza, where all water treatment facilities have been destroyed. Palestinians now need low-cost technology they can make themselves with no need for batteries or electricity. Let’s hope this young scientist gets the financial support she needs to make her technology spread worldwide!