An apparatus for controlling the distribution of a fluid along a supply line configured to supply a user includes a first hydraulic valve located along the supply line and provided with an inlet, which receives fluid in transit in the supply line; an outlet, which transmits fluid through the first valve to make it continue along the supply line, or which receives fluid coming from a portion of the supply line downstream of the first valve; and a discharge, which discharges outside of the supply line, through the first valve, fluid present in the supply line and coming from a portion of the supply line downstream of the first valve. A second hydraulic valve is operatively located along the supply line at a point downstream from the first valve and provided with an inlet, which receives fluid coming from the outlet of the first valve; an outlet, which transmits fluid through the second valve to make it continue along the supply line; and a bypass inlet, which receives fluid drawn from the supply line at a withdrawal point upstream of the first valve and brought directly to the second valve by means of a bypass duct branching off from the supply line upstream of the first valve.