The mass media has an important role in informing the general public about emerging health risks. Content-based studies of risk communication in the media have revealed a tendency to exaggerate risks or simplify science, but linguistic studies in this area are still scarce. This paper outlines a corpus based investigation of media reporting on the discovery of minute amounts of Endocrine Disrupting Compounds (EDCs) and Pharmaceuticals and Personal Care Products (PPCPs) in drinking water. There is no concrete evidence that these residuals pose any threat to human health in such minute amounts, but the natural scientific uncertainty and professional risk language surrounding contaminants have sparked considerable media attention in both the US and the UK. In fact, these have lead to Congress-level discussions about changes to the way contaminants are regulated in the US. Comparing media reports that appeared in newspaper articles, magazines and web-based media in the UK and the US with those to appear on water company and public health organisation websites, our use of quantitative and qualitative corpus linguistic techniques revealed strikingly different patterns for the language used to represent contaminants and their risks. While water organisation reports demonstrated a clear tendency to downplay the probability and severity of the risk posed by contaminants, the linguistic and rhetorical features identified in media texts place the focus on the potentiality of contaminants as an unconfirmed threat to public and environmental health. We discuss the implications of these findings for the role of the media in the communication of health risks, and for communication about water contaminants.