Gas distribution system for feeding to an engine powered by alternative gas fuel, gas contained in a first gas tank and at least in a second gas tank , said system having a first gas conduit connecting an output of the first gas tank and a second gas conduit connecting an output of the second gas tank , wherein valve means are provided on the conduits to select the gas tank having the highest gas pressure and suppling to the engine the gas provided by the selected tank; said valve means further comprise at least first check valve that is interposed in the first gas conduit and a second check valve that is interposed in the second gas conduit so that the first and the second valves are placed on opposite sides of a merge point where the first conduit and the second conduit meet and may be opened by the difference of pressure of the gas in the first/the second gas conduit (12 e 14) and the merge point ; a supply gas conduit connects the merge point and a pressure regulator supplying the gas to the engine ; the supply gas conduit contains the gas originated by the gas tank having the highest pressure; the gas distribution system is characterized in further comprising a gas recharge conduit that has one free end (24-a) provided with a check-valve and another end (24-b) that bifurcates in a first branch that is connected with the first gas conduit in a position between the first check valve and the first gas tank and a second branch that is connected with the second gas conduit in a position between the second check valve and the second gas tank ; the first branch is provided with a third check valve that is opened when pressurized gas is supplied to the gas recharge conduit ; the second branch is provided with a fourth check valve that is opened when pressurized gas is supplied to the gas recharge conduit . said valve means further comprise at least first check valve that is interposed in the first gas conduit and a second check valve that is interposed in the second gas conduit so that the first and the second valves are placed on opposite sides of a merge point where the first conduit and the second conduit meet and may be opened by the difference of pressure of the gas in the first/the second gas conduit (12 e 14) and the merge point ; a supply gas conduit connects the merge point and a pressure regulator supplying the gas to the engine ; the supply gas conduit contains the gas originated by the gas tank having the highest pressure; the gas distribution system is characterized in further comprising a gas recharge conduit that has one free end (24-a) provided with a check-valve and another end (24-b) that bifurcates in a first branch that is connected with the first gas conduit in a position between the first check valve and the first gas tank and a second branch that is connected with the second gas conduit in a position between the second check valve and the second gas tank ; the first branch is provided with a third check valve that is opened when pressurized gas is supplied to the gas recharge conduit ; the second branch is provided with a fourth check valve that is opened when pressurized gas is supplied to the gas recharge conduit . <EOS>