Abstract: The invention relates to an apparatus for keeping a rain water well unfrozen. The apparatus comprises a cover (12), walls (13) and an outlet (15), which defines an air space (16) of the well above the outlet and a water space (17) of the well below the outlet. According to the present practice, the whole surface area of the water in a rain water well is in contact with open air, which results in that the well freezes relatively easily under the joint influence of wind and frost. This problem is solved according to the invention in such a way that the apparatus comprises a funnel (1) positioned under the cover (12) of the well and a flow tube (5), the cross section of which is substantially smaller than the diameter of the well and which tube extends from the lower part of the funnel (1) under the water surface of the well.