A method for mounting a kit for fixing a tap to a partition, particularly to a plasterboard partition, this method comprising the successive steps of: a) pre-mounting at least one connector of the kit to a plate of the kit, each connector comprising a first endpiece for connection to a water supply pipe and a second nozzle for connecting the valve, the second endpiece defining a longitudinal axis, having an outer surface of polygonal section and having an outer thread, b) connecting each connector to a corresponding water supply pipe, c) making at least one hole in the partition for the passage of the second endpiece of each connector through the partition, d) placing the partition in front of the plate, e) pulling the second connection endpiece of each connector through the at least one hole of the partition, and f) fixing the plate on a rear face of the partition, on the side opposite the location provided for the tap, characterized in that: - between steps e) and f), the method comprises a step consisting in adjusting the length over which each second endpiece protrudes axially relative to a front face of the partition, whereas the second endpiece of each connector is received inside a corresponding ring of the kit attached to the plate during the pre-mounting of step a), the ring having an inner contour complementary to the outer shape of the endpiece, the ring blocking the rotation of said second endpiece about its longitudinal axis, but not preventing the second endpiece from sliding parallel to the longitudinal axis, and - step f) comprises immobilizing each second endpiece along its longitudinal axis, using a respective nut, the nut being screwed around said second endpiece, then screwed to the corresponding ring, each nut bearing against the front face of the partition. a) pre-mounting at least one connector of the kit to a plate of the kit, each connector comprising a first endpiece for connection to a water supply pipe and a second nozzle for connecting the valve, the second endpiece defining a longitudinal axis, having an outer surface of polygonal section and having an outer thread, b) connecting each connector to a corresponding water supply pipe, c) making at least one hole in the partition for the passage of the second endpiece of each connector through the partition, d) placing the partition in front of the plate, e) pulling the second connection endpiece of each connector through the at least one hole of the partition, and f) fixing the plate on a rear face of the partition, on the side opposite the location provided for the tap, - between steps e) and f), the method comprises a step consisting in adjusting the length over which each second endpiece protrudes axially relative to a front face of the partition, whereas the second endpiece of each connector is received inside a corresponding ring of the kit attached to the plate during the pre-mounting of step a), the ring having an inner contour complementary to the outer shape of the endpiece, the ring blocking the rotation of said second endpiece about its longitudinal axis, but not preventing the second endpiece from sliding parallel to the longitudinal axis, and - step f) comprises immobilizing each second endpiece along its longitudinal axis, using a respective nut, the nut being screwed around said second endpiece, then screwed to the corresponding ring, each nut bearing against the front face of the partition.