Improved hand hygiene efficiently prevents the major killers of children under the age of five years in Ethiopia and globally, namely diarrhoeal and respiratory diseases. Effective handwashing interventions are thus in great demand. Evidence- and theory-based interventions, especially when matched to the target population's needs, are expected to perform better than common practice. To test this hypothesis, we selected two interventions drawing on a baseline questionnaire-study that applied the RANAS (Risk, Attitudes, Norms, Abilities, Self-regulation) approach and focused on the primary caregivers of households in four rural, water-scarce kebeles (smallest administrative units of Ethiopia) in southern Ethiopia (N = 462). The two interventions were tested in combination with a standard education intervention in a quasi-experiment, as follows: kebele 1, education intervention, namely an f-diagram exercise, (n = 23); kebele 2, education intervention and public-commitment (n = 122); kebele 3, education intervention and tippy-tap-promotion (i.e. handwashing-station-promotion; n = 150); kebele 4, education intervention, public-commitment and tippy-tap-promotion (n = 113). In kebeles 3 and 4, nearly 100% of the households followed the promotion and invested material and time to construct for themselves a tippy-tap. Three months after intervention termination, the tippy-taps were in use with water and soap being present in up to 83% of the households (kebele 4). Pre-post data analysis on self-reported handwashing revealed that the population-tailored interventions, and especially the tippy-tap-promotion, performed better than the standard education intervention. Tendencies in observed behaviour and a recently developed implicit self-measure pointed to similar results. Changing people's hand hygiene is known to be a challenging task, especially in a water-scarce environment. The present project suggests not only to apply theory and evidence to improve handwashing interventions' effectiveness, but also emphasizes the relevance of tailoring interventions to the target population.
