Descaling hot-beverage producing machines

A hot-beverage producing machine comprising

• a water tank;
• a hydraulic circuit comprised of a water heater, a pump and a connection of the hydraulic circuit to the water tank;
• and a descaling device for descaling a hydraulic circuit of a hot-beverage producing machine the descaling device comprising:
• a descaling-chemicals reservoir provided with:
• a top portion;
• a bottom portion, configured for coupling to a bottom connection of a water tank;
• an outlet port arranged at or near the bottom portion and having an openable closure member for establishing a flow connection of the descaling-chemicals reservoir with the hydraulic circuit of the hot-beverage producing machine;
• a water inlet port;
• a water flow passage for flow communication between the water inlet port and the descaling-chemicals reservoir;
• wherein the water inlet port and the outlet port can be placed in fluid communication, such that water can be sucked through the water inlet port, caused to flow through the descaling-chemicals reservoir and discharged through the outlet port wherein that said water tank has a bottom connection forming a water outlet passage, said bottom connection being configured and arranged for connecting the descaling-chemicals reservoir to the water outlet passage and forming a flow connection between the descaling-chemicals reservoir and the hydraulic circuit of the hot-beverage producing machine.