In July 2017 the then newly formed Swiss association Gravit’eau had the opportunity to test a self-developed handwashing station at the German Music Festival Feel. The handwashing station recycles the greywater with an ultrafiltration module and activated carbon, without the use of electricity and chemicals. The system is completely self-sufficient and only needs to be filled once in the beginning. The water can come from any ground- or surface water source, as turbidity or microbiological contamination is filtered by the membrane. The membrane filters the water using only gravity at an estimated 3-5 l/m2/h. A simple foot pump provides the pressure for handwashing, while naturally limiting the use of water.

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At the festival, the system was tested under great stress. Approximatively 250 people washed their hands every hour. This accounts to a total of around 15’000 handwashing occurrences over the running period of 60 hours. People accepted the system very well and were keen to use it and understood the principle very well. The insights gained during that test both forma technical and user centred design point of view helped to develop the further prototypes.