This article describes how a university and a museum have worked together to create a "How science works" workshop entitled "What's in our water?" The workshop teaches students about the continuing pollution from a disused coal mine, how the pollution is cleaned up using a state-of-the-art treatment works and how scientists monitor the site. The article also discusses how and why the workshop was developed, the science of acid minewater drainage and the strengths and weaknesses of outreach events of this nature.