The device has a liquid delivery unit (10) actuated by actuation signals from a control device for dispensing liquid into a connecting line (21) of a surgical instrument (20) with a manually operated outlet nozzle (22). Measuring devices e.g. humidity sensor (41), pressure sensor (42) and positioning sensor (43), generate measurement signals for displaying amount of the liquid dispensed on a display or registration device (31) after connecting the surgical instrument to the liquid delivery unit. The measuring devices have a filing sensor and generate a filling signal. An independent claim is also included for a method for operating a water-jet surgery device.
