Faecally contaminated drinking water, a leadingcause of diarrhoeal diseases, is currentlyconsumed by an estimated 1.8 million peopleglobally1. Diarrhoeal diseases are a leading causeof death for children under five years old2,3. TheUnited Nations鈥?Sustainable Development Goal(SDG) 6 calls for universal access to safe drinkingwater. Groundwater is a major source of drinkingwater globally1 鈥?in many regions it is the onlysource of drinking water in the dry season 鈥?andfaecal contamination of groundwater remains amajor concern.There is now strong evidence for the suitability of tryptophan-like fluorescence (TLF) for assessing therisk of faecal contamination in groundwater. TLF provides a robust and rapid in-situ screening tool toenable more rapid monitoring of drinking water quality to help assess progress towards SDG 6.