The invention relates to transdermal therapeutic systems (TTS) comprising a backing, a reservoir layer containing at least one pharmaceutical active ingredient, and an adhesive. Said transdermal therapeutic systems are characterised in that they are able to continuously adhere to the surface of the skin over a long period of time. During said long period of time, a) there is at least one time interval during which the TTS adhering to the surface of the skin is intensively exposed to water, and b) the active ingredient is transdermally released. The invention also relates to a method for the continuous transdermal release of at least one pharmaceutical active ingredient over a long period of time.