The invention relates to a device (100) for providing liquid for a beverage machine (110), comprising a water tank (10) having at least one water inlet (11) which can be connected in a controllable manner to a water connection in order to fill the water tank (10), a control device (30) for controlling the water inlet (11) that can be connected in a controllable manner, and at least one filling level sensor (41, 42) for generating a signal which indicates at least whether or not a first filling level of liquid inside the water tank (10) has been reached or exceeded. In order to achieve easier cleaning, in particular descaling of the device (100), the at least one filling level sensor (41, 42) can be or is connected to the control device (30) to transmit the signal and the control device (30) is designed to control the water inlet (11) according to the signal of the at least one filling level sensor (41, 42) and according to at least one operating mode, wherein the operating mode is either a filling mode or an emptying mode. Furthermore, a controllable drainage device (44) for draining liquid from the water tank (10) is present.