The invention relates to an infusion device for therapeutic use comprising a water-tight cover 1 in the form of a housing, a housing part or a receptacle for holding said infusion device and a control system which is used for controlling the cover 1 water tightness and comprises c) a medium arranged in the cover 1 and characterised by at least one physical or chemical quantity variable according to the cover water tightness and d) an information system 6, 8, 9 which automatically transmits at least one information signal when said quantity changes in such a way that the loss of the cover 1 water tightness is indicated.