Field report: Roofwater harvesting on the coastal islands of Guinea-Bissau: rainwater tank construction adapted to the local context
The Republic of Guinea-Bissau in West Africa is not a well-known country. The islands in the south-west are part of a flat and ‘salty’ coastal landscape with severe drinking water problems. The NGO ‘Iagu Limpo – Tabanka San’ (Clean Water – Healthy Village) has adapted cement water tanks – called Balanta tanks – to the context in this part of the world. Using clay blocks as a stable and inexpensive formwork avoids the problem of an unstable mould and thus reduces materials needed. More than 1,000 of these tanks exist in Guinea-Bissau and numbers are increasing fast. A MAPP (Method of Assessment of Projects and Programmes) exercise has shown the importance users attach to the tanks; they are an integral part of their lives. People appreciate them as a source of clean water for drinking, whereas water for other purposes (such as cleaning, washing) usually comes from wells (often with brackish water). Readers interested in this innovative and simple way to build and spread rainwater tanks can join training courses or send masons to work with trained masons in Guinea-Bissau.