Written by Chad Staddon, Professor of Resource Economies and Policy.
A lack of access to safe, piped water services in many parts of the world means that alternative water supplies, such as rainwater harvesting (RWH), are often all that is available. However some studies have shown that RWH may pose a health risk because of its potential to carry microbial pathogens through wet deposition (bonding of chemicals in the air before hitting the roof), transit via the catchment area (usually a rooftop), drainage gutters and pipes, and the residence time in the storage tank itself. Indeed, water quality testing undertaken by a UWE Bristol team in southwestern Uganda in 2019 suggested that up to 50% of water samples from RWH systems could be contaminated in excess of WHO limits.
To improve the microbiological quality of stored drinking water, ceramic pot filters (CPFs) may be a robust point-of-use technological solution. Through a combination of mechanisms including ultrafiltration, adsorption and biofilm metabolism CPFs have been demonstrated to be effective at removing >99% of protozoa and 90-99% of bacteria. CPFs are associated with a 60-70% reduction in diarrheal disease incidence reported by users in some studies.
In 2018 and 2019 UWE Bristol staff and students worked to better understand the extent of the water quality challenge associated with RWH and to options assess possible solutions including granular media, solar disinfection and ceramic pot filters. Now, the UWE Bristol Healthy Waters team, including Chad Staddon, Tavs Jorgenson and Jiseon You, is working to determine if CPFs can be manufactured in accordance with appropriate technology principles stipulating that technologies should be locally reproducible and maintainable with essentially existing skills and resources. The team aims to develop a trial for locally produced CPFs using existing ceramics making processes including open pit firing during 2022. If successful the team hopes to support and encourage the scale up of production by local producer groups, enterprises or cooperatives, thus addressing capacity gaps identified in earlier research.