A drip-type coffee-maker includes a water reservoir (1) supplying a water-heater with continuous circulation (6), and a device (9) for treating the water in the reservoir with a water-soluble scale preventive agent. The water treating device (9) includes an element (10) for measuring out an amount of scale preventive agent (23) which is determined on the basis of the volume of water supplied to the water-heater (6) and which is injected into the water.