PURPOSE: To provide an inexpensive water supply facility to a stone machining apparatus having a relatively simple structure without necessity of using a large quantity of a flocculant.

CONSTITUTION: A water supply facility for supplying water for machining a stone to a stone machining apparatus 1 comprises a water storage tank 2, a filter 4 having a gravity type filtering tank 3, a first water supply unit 5 for taking the water in the tank 2 from a water intake port 10 provided at a predetermined height from the bottom 2a of the tank 2 to supply to the apparatus 1, and a second water supply unit 6 for supplying the water used at the apparatus 1 to the filter 4. The facility also comprises a third water supply unit 7 for recovering the water passed through the filter 4 to the tank 2, and a fourth water supply unit 8 for taking the water in the tank 2 from the port 10 provided at the bottom 2a of the tank 2 to supply to the filter 4.