Abstract. This paper presents some design-oriented reflections about a design idea, the WaterCalls. This design concept is informed by findings from an ethnographic study of emergency service work. Two main components constitute WaterCalls – an ambient display consisting of bowls with water and a call-queue in a graphical interface. The purpose is to support cooperation between several operators who work at different emergency service centres. One benefit with ambient displays in the emergency service centre is that information, which is currently not available in the setting, may be displayed in an unobtrusive way. In the paper we suggest that it is important to consider how the ambient displays come into real use, and fit into the work people actually do, namely their work practices. For the development of interfaces like this it is crucial to take into consideration how they are used in combination with more traditional graphical interfaces and other artefacts.