Eliodomestico is a purification system for private use developed for third world countries. The system works on solar energy and is able to purify five litres of water every day, even in the driest and hottest weather conditions. The design is open-source and the local craftsmen can produce this filtering system with only a few resources. It is easily made with sustainable materials, such as terracotta, anodised zinc and recycled plastic. Eliodomestico works as a reversed coffee filter: during the day the sun heats up the water, which allows condensation to take place. As a result, 5 litres of freshwater a day can be produced. The project is perfectly suitable for third world countries where there is a higher risk of drought and pollution. Eliodomestico functions without filters or electricity and requires little maintenance. The Italian designer Gabriele Diamanti has been one of the 12 finalists in the Prix Émile Hermès.