A working prototype of the Solarstill Box installed at Lake Eyasi in Tanzania. The device converts contaminated and saline water into drinking water using solar energy alone. [Provided by KAIST]
A working prototype of the Solarstill Box installed at Lake Eyasi in Tanzania. The device converts contaminated and saline water into drinking water using solar energy alone. [Provided by KAIST]

A new desalination device that purifies contaminated water into clean drinking water using only sunlight — no electricity or fuel required — has been developed, offering a potential solution for low-resource countries struggling with water scarcity and pollution.

KAIST announced Friday that the Solarstill Box, a solar-powered water purification and desalination device developed by a research team led by Bae Sang-min, a professor in the Department of Industrial Design, has won the Red Dot: Best of the Best — the top prize in the social impact category — at the Red Dot Design Award: Design Concept 2026.

The Red Dot Design Award ranks among the world's three most prestigious design competitions, alongside Germany's iF Design Award and the United States' International Design Excellence Awards (IDEA). The Best of the Best distinction is the highest honor within the competition, awarded to entries judged most innovative and accomplished in their respective categories.

The recognition goes beyond acknowledging the device's design quality. It represents international validation that design can address a shared human challenge — access to clean water — and generate lasting social value.

The Solarstill Box is a low-cost purification and desalination device that converts seawater or water containing salt and contaminants into drinking water through solar distillation. It was developed for off-grid communities — those without access to public infrastructure — in coastal areas, saline zones or regions dependent on polluted water sources. The device produces clean water using solar energy alone, with no electricity, fuel or separate filters required.

A stepped tray inside the device increases the surface area over which water evaporates, boosting solar distillation efficiency. As the vapor condenses on a transparent cover, contaminants including salt, heavy metals and bacteria are naturally separated, leaving only clean water to be collected.

Professor Bae Sang-min (in blue vest) and his research team conduct field research and a co-design workshop with local residents in Tanzania as part of the Solarstill Box development process. [Provided by KAIST]
Professor Bae Sang-min (in blue vest) and his research team conduct field research and a co-design workshop with local residents in Tanzania as part of the Solarstill Box development process. [Provided by KAIST]

The Solarstill Box is also built from flat components based on Plaveneer sheets, allowing it to be produced and shipped in flat-pack form. Anyone can assemble it on-site in about 20 minutes, and only damaged parts need replacing, keeping maintenance costs low. Rather than delivering one-time relief supplies, the design enables local residents to install and manage a sustainable drinking water system themselves.

Building on the award, the research team plans to work with World Vision to commercialize the product and establish a local distribution model. Over the longer term, the team aims to expand into a cooperative-based operating model in which community members participate directly in manufacturing, retail and maintenance — supporting both the resolution of drinking water challenges and the sustainable development of local communities.

"We hope the Solarstill Box will provide real, practical help to communities in need of clean water, and that it will spread as a sustainable drinking water system that residents can operate on their own," Bae said.


nbgkoo@heraldcorp.com