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2022 – Petra Wadström

The Solvatten innovation is saving lives in refugee camps, war zones and other places where a lack of clean water has reached crisis proportions.
Solvatten provides a container that users fill with contaminated water and place in the sun. A couple of hours later the water is clean and safe to drink, and has also been heated up for household and healthcare purposes.
“The aim is to give everyone access to clean, hot water, using no fossil fuels at all,” says inventor Petra Wadström. She is the recipient of the KTH Great Prize 2022.

Petra Wadström portrait outdoors in sunshine
Petra Wadström, designer, artist and the innovator behind Solvatten receives the KTH Great Prize 2022. Today the technology is used in more than 20 countries, improving the lives of more than half a million people.

KTH Great Prize 2022 goes to innovator behind solar powered water purifier

When Wadström was living in Australia with her family in the late 1990s, she was struck by the intensity of all the solar energy reaching the ground without being harnessed.

She came up with the idea for Solvatten, an idea that gradually grew to the point where she could test materials, functionality and design – all to maximise the effect of the sun’s heat and UVB radiation.

“Today, Solvatten is improving the lives of over half a million people around the world, and I’ve been longing to talk about it,” says Wadström.

Petra Wadström portrait picture
“In my lectures for university students, I feel it’s important to inspire new innovators by showing that it is possible to make a difference. You can often use a problem as a means of achieving a positive solution.”

At the time of this interview she is planning an upcoming trip to Kenya, to visit ongoing Solvatten projects.

“We also work in refugee camps alongside UNHCR and help out with training and education in water and hygiene. Several projects are under way in the driest parts of Africa, such as Mali, Niger, Uganda and Burkina Faso,” she says.

“Something we can see in all our projects is that entire communities benefit when women and girls avoid that heaviest of everyday tasks: lugging home wood and starting a fire to boil and purify water. This means that girls can go to school more often, and that women have more valuable time.”

A woman in Africa cleaning vegetables with sun purified water
“At present, mothers living in poverty with children under five are the main users of Solvatten units for their families. We are reaching new users by communicating at all levels – from clans and local organisations, to the UN.”

Since water is cold when pulled up from a well, even in hot countries, buckets and containers of dirty water are often put out in the sun to warm up. That water is used carelessly for operations and childbirth.

“Using the water like this causes a growth explosion of microorganisms when it reaches temperatures of up to 40 degrees Celsius. But with Solvatten, all the viruses, parasites and bacteria are killed by the UVB light, and that’s a lifesaver, particularly in healthcare,” says Wadström. She says that the key is to achieve at least the same level of purification as if the water had been boiled.

A Solvatten unit costs around €110, and lasts, as Wadström puts it, “a childhood” – seven to 10 years – without having to replace any parts.

“This makes it a cost-effective solution per litre of clean, hot water. Our calculations also show that a unit saves up to 10 tonnes of emissions over its lifetime, and fewer trees are harvested as there’s less need for firewood and charcoal.”

"A great need for clean water in vulnerable and disaster-struck areas worldwide"

Wadström adds that there is a great need for clean water in vulnerable and disaster-struck areas worldwide, and not just in developing countries. And Solvatten units can also be used in parts of the northern hemisphere at the time of year when sunlight is at its most intense.

“My vision is that all people should live in health and dignity, with access to clean and hot water at home. Imagine that,” she says. “The world would certainly look very different from how it does today.”

Text: Katarina Ahlfort
Photo: Mikael Sjöberg

For more information about KTH Great Prize 2022 contact:
Contact Petra Wadström:, +46709253601

How the Solvatten technology works

  •  The two-part black container is filled with water.
  • The Solvatten purifier uses solar heating and UV radiation to purify the water effectively: the sun’s ultraviolet UVB rays are released through UV-transparent surfaces, and the water is heated against the black inside of the container. The resulting synergies render pathogenic microorganisms harmless.
  • The Solvatten container also has a filter that removes water organisms, making the water less turbid.
  • Once the process is finished and the water is clean, according to WHO guidelines for clean water, an indicator shows a green smiley face.
  • It takes two to five hours to clean 10 litres of water of harmful microorganisms, which can otherwise cause dysentery, typhoid fever and cholera.

Motivation for the KTH Great Prize 2022

“Clean water is crucial to people’s health, opportunities and quality of life. It is also a key issue for future generations and the possibilities for sustainable development. Petra Wadström is a unique, single-minded problem-solver who with her innovation, Solvatten, has changed the lives of many people – and particularly women – around the world. Petra Wadström has created a simple yet clever, ingenious and sustainable construction, enabling water to be purified by the sun alone. This invention will allow more people access to vitally important clean water every day.
Petra Wadström is a highly deserving recipient of the KTH Great Prize .
The prize amount this year is SEK 1.2 million (approx. €109,000).”

Belongs to: About KTH
Last changed: Mar 10, 2023
2022 – Petra Wadström
2021 - Johan Rockström
2020 Tom Alandh
2019 – Dilsa Demirbag-Sten
2018 – Kristina Edström
2017 - Jonas Gardell
2016 - Stina Ehrensvärd
2015 - Max Tegmark
2014 - Sara Snogerup Linse
2013 - Robyn
2012 - Daniel Ek
2011 - Mikael Eriksson
2010 - Hans Rosling
2009 - Niklas Zennström
2008 - Gunilla Pontén
2007 - Christer Fuglesang
2006 - Mathias Uhlén