Approximately 200 million people, mainly concentrated in rural areas of the Great East African Rift Valley, suffer from fluorosis caused by excess of fluoride naturally contained in water. This study employs the RANAS (Risk, Attitude, Norm, Ability, Self-regulation) model to understand how behavioural factors influence Tanzanian rural communities’ willingness to pay for fluoride-free water obtained from a new defluoridator device. Results show that perceived risk, knowledge, attitudes and descriptive norms significantly influence the adoption of the proposed healthy behaviour. Policy implications are discussed taking into account how rural communities could achieve equitable and affordable access to safe water.