Abstract: The present invention relates to a digital water temperature reading device for a spa, swimming pool and whirlpool. A temperature probe is located inside an adaptor screwed in one of the waste openings of a filtration or pumping system. The adaptor fills in a double function, to serve as receptacle for the temperature probe and to replace the waste plug otherwise located in the opening. The adaptor includes a dome receiving a contact point of the temperature probe in its concave part and getting in touch with the bath water in its convex part. The dome is surrounded by a circulation channel facilitating the heat transfer between the water and the contact point. The temperature probe is maintained in place by means of a plug equipped with a slot to engage a wire connected to the temperature probe and connected, by a wire or an emitter, to a digital monitor. The slot could be self-sealing.