Water inlet system in a toilet cistern

A system for feeding water into a flush tank, comprising, in the mounted position:

• a body including in its upper part an air intake port;
• a first pipe provided in the body, configured to be connected, at its upstream end, to a water supply network;
• a second pipe provided at least partly in the body, having an upstream end in fluid communication with the first pipe via an opening, and a downstream end located lower than the upstream end, the second pipe including a lumen located substantially vertically in line with the air intake port, the peripheral edge of the lumen defining a bearing surface;
• a valve which is mounted on the body and which, according to the height of water in the tank, can be in a closed state in which the valve shuts off said opening sealingly, or in an open state in which the opening is released;
• a shutter movable between:
• a low position, in which the shutter rests on the bearing surface while providing in the lumen a communication space between the inside and the outside of the second pipe, the air intake port being clear;
• and a high position, in which the shutter shuts off the air intake port;
• wherein the water feed system further comprises a flow modification device which is fastened to the second pipe downstream of the lumen and which creates a back pressure when water flows through the system towards the tank, and in that the shutter has a density greater than 1.4, thus preventing the shutter it from floating, so that, starting from an inactive state of the system where the flap is in the closed position and the shutter is in the lower position, the opening of the valve and the resulting flow of water into the second pipe causes the shutter to move to its upper position under the effect of the back pressure created by the flow modification device.