Abstract: Non-return valve, in which, between the non-return valve assembly and the end of the valve body, which can be connected to a tap, emptying ports are provided and a shut-off diaphragm is supported, which, when the tap is closed, frees the run between the inside of the tap and the emptying ports and, when the tap is open, separates the inside of the tap from the emptying ports.

Abstract: A non-return valve for supply cocks, comprising an integral cup-shaped valve body (8) accommodating a substantially rigid washer (14) forming a seal with respect to the supply cock (2) and having flow apertures (16), as well as a flexible membrane (15) located underneath and self-positioning, during closure, against the said substantially rigid washer (14) so as to close the said flow apertures (16) of the same (14) and move away from the said flow apertures (16) under the pressure of the water supplied. The substantially rigid washer (14) and the flexible membrane (15) may advantageously be joined together so as to form a composite washer (28). The valve (1) proposed has a small number of components and can be very easily assembled. The substantially rigid washer (14), or the composite washer (28), has an external thread (14a)so that the said washer (14; 28) can be screwed into the thread (8b) of the cup-shaped portion (8a) of the valve body (8).