A new method for cleaning household water supplies in rural communities in Nepal is being developed by an international team of scientists.
The solution removes harmful bacteria from the water by inserting non-toxic metal catalysts into containers which sit outside residents' homes and feed their points of supply.
The technology was originally developed for use in self-cleaning period products, as part of a Gates Foundation-funded collaboration between researchers at Cardiff University and Tribhuvan University.
The SunPad, which kills up to 99.99% of bacteria, needs to be rinsed with water after use and left to dry in the sun to kick start the cleaning and disinfecting process.
The scientists are now working together with researchers at the Nepal Academy of Science and Technology (NAST) to adapt SunPad's technology to clean water supplies in communities like the Kathmandu Valley, where up to 70% of sources are contaminated with waterborne pathogens.
Heavy metal contamination of Nepali water sources will also be targeted by the international team, addressing the arsenic content in regions such as the Southern Terai regions, which exceeds 50 times the safe exposure limit.
Dr Jennifer Edwards, a Reader in Cardiff University's School of Chemistry, said: "It's really exciting to see the technology that has led our self-cleaning period products to field studies in Nepal, already finding new applications in the country."
The idea is to fix our catalyst within the tanks which store water for households in rural Nepali communities so the water can be decontaminated in-situ, avoiding the need for a continuous supply of energy or chemicals for water processing.
"Not only that, but the materials are also designed to be synthesised using readily available, low-cost, chemicals and without the need for advanced semiconductor equipment. This means they are readily transferable to geographies such as Nepal with fledgling chemical industries."
The reusable nature of the team's solution also provides an additional layer of resilience in case of supply chain disruption during monsoon season, extreme weather events and even natural disasters such as earthquakes and landslides, which are common in Nepal.
The idea has developed from a water workshop funded by the Higher Education Funding Council Wales (now Medr) held in Kathmandu in February 2024, where solar disinfection was suggested as a solution to household-scale water decontamination.
This demonstrated that using the SunPad technology for water purification purposes may be technically feasible and fit with existing practices in Nepal.
Since then, the team from NAST has spent a summer in Cardiff to push the technology further.
On a return visit to Nepal, the Cardiff team donated a lighthouse photoreactor to their collaborators. Identical to those used in their labs in Wales, the reactor will ensure comparable experimental results between the two teams.
Watch a video day in the life of SunPad researcher Dr Katrina Duggan on YouTube
The water quality in Nepal right now is not so good but thanks to the impact of our research it is improving. The mortality and morbidity rates are decreasing in Nepal as well. So, this collaboration will build on these successes as we continue to try and get more pure water for our country.
"This problem is so important to Nepali society because without pure water we cannot live. Many people in rural communities and even here in Kathmandu are still accessing untreated water supplies and this is leading to disease, diarrhoea and dysentery.
"The photoreactor the Cardiff team has donated will be crucial in supporting us to carry out experiments on these water supplies.
"In this collaboration, we will use the reactor to assess how the catalysts developed in Cardiff can remove microbiological contaminants in real Nepali water samples. With that information, we will be able to design more active catalysts and make water supplies safer for everyone in Nepal."
The institutions plan to sign a memorandum of understanding together, to formalise their partnership working, so funding applications can be submitted jointly and reflect the research interests and priorities of all parties.
This kind of tech transfer has always been the direction of travel for the work we've done with support from the Gates Foundation. And so, for this related project, it means working with colleagues from NAST on knowledge exchange, training and capacity building, so that together, we can target new ways to clean water in Nepal.
This project has received funding from Welsh Government's Taith Research Mobility programme and Medr's institutional allocation of International Science Partnerships Funding (ISPF) to support Official Development Assistance (ODA) activities.
