Ensuring a good quality water supply that is free from contamination is key to meeting the global goal of providing everyone with access to safely managed water by 2030. This brief summarises the findings of an in-depth review of WaterAid’s work, aimed at safeguarding water quality carried out in 2019–20. 20 country teams participated in the review, which focused on water quality challenges encountered in different locations and the interventions deployed to address them.