A drain for sanitary fixtures, comprising: - a body that can be fastened to a sanitary fixture, for example a sink, provided with a base and a top, wherein the base comprises an opening for draining water and the top delimits a mouth for the inlet of water in the body of the drain; - a plug housed in the body of the drain and movable with respect to it between a lowered position, at which the plug does not intercept the mouth, thus allowing the flowing of water, and a raised position, at which the plug closes the mouth and prevents the flowing of water, - a lifting mechanism to lift the plug, intended to bring back the plug to the raised position, in response to a stress exerted by the user, comprising a first elastic element deformable during the descent of the plug, - an overflow mechanism, combined with the plug and configured to allow the plug to automatically lower, thus opening the mouth, when a threshold value of the water pressure acting on the plug itself is exceeded, wherein the plug comprises a first magnetic element and the lifting mechanism comprises a second magnetic element, wherein the first magnetic element is in-between the base of the body and the second magnetic element, and wherein the first elastic element exerts a thrust on the plug towards the relative raised position, and wherein, in the raised position of the plug, the first magnetic element and the second magnetic element are magnetically coupled, wherein the plug comprises a stem extending along a longitudinal axis between a lower portion and an upper portion, and a head cooperating with the inner edge of the mouth for sealing the mouth itself and for preventing the flowing of water, wherein the head is coaxially fitted on the upper portion of the stem and is slidable relative thereto between a raised position and a lowered position with respect to the upper portion of the stem, characterised in that the overflow mechanism comprises a third magnetic element arranged on the upper portion of the stem, and a fourth magnetic element integral with the head and in-between the base and the third magnetic element, and wherein, in the raised position of the plug, corresponding to the raised position of the head, the third magnetic element and the fourth magnetic element are magnetically coupled and wherein, when a threshold value of the water pressure acting on the head is exceeded, the third magnetic element and the fourth magnetic element are automatically uncoupled, causing the descent of the head towards the lowered position, corresponding to the opening of the mouth. - a body that can be fastened to a sanitary fixture, for example a sink, provided with a base and a top, wherein the base comprises an opening for draining water and the top delimits a mouth for the inlet of water in the body of the drain; - a plug housed in the body of the drain and movable with respect to it between a lowered position, at which the plug does not intercept the mouth, thus allowing the flowing of water, and a raised position, at which the plug closes the mouth and prevents the flowing of water, - a lifting mechanism to lift the plug, intended to bring back the plug to the raised position, in response to a stress exerted by the user, comprising a first elastic element deformable during the descent of the plug, - an overflow mechanism, combined with the plug and configured to allow the plug to automatically lower, thus opening the mouth, when a threshold value of the water pressure acting on the plug itself is exceeded, wherein the plug comprises a first magnetic element and the lifting mechanism comprises a second magnetic element, wherein the first magnetic element is in-between the base of the body and the second magnetic element, and wherein the first elastic element exerts a thrust on the plug towards the relative raised position, and wherein, in the raised position of the plug, the first magnetic element and the second magnetic element are magnetically coupled, wherein the plug comprises a stem extending along a longitudinal axis between a lower portion and an upper portion, and a head cooperating with the inner edge of the mouth for sealing the mouth itself and for preventing the flowing of water, wherein the head is coaxially fitted on the upper portion of the stem and is slidable relative thereto between a raised position and a lowered position with respect to the upper portion of the stem, characterised in that the overflow mechanism comprises a third magnetic element arranged on the upper portion of the stem, and a fourth magnetic element integral with the head and in-between the base and the third magnetic element, and wherein, in the raised position of the plug, corresponding to the raised position of the head, the third magnetic element and the fourth magnetic element are magnetically coupled and wherein, when a threshold value of the water pressure acting on the head is exceeded, the third magnetic element and the fourth magnetic element are automatically uncoupled, causing the descent of the head towards the lowered position, corresponding to the opening of the mouth.