Water quality is an integral part of water security. Measuring the physico-chemical indicators for water quality can provide an objective picture of water health, but it does not provide information on lived experiences related to water quality, expectations of water resources, nor how the quality of water affects its usage. Perceptual information and traditional ecological knowledge on water quality can help to understand interactions between water and people, and thereby support locally appropriate sustainable water resource strategies. Accordingly, our project sought to collect and synthesise insights from local perspectives on water quality in the upper Santa River basin, Peru, a region where water quality directly relates to people’s livelihoods. Perceptual data was collected via the Nuestro Rio mobile app (N = 149) as well as walking interviews (n = 84) (July-August 2021) in two ...