A fuel filtration and separation assembly of a fuel circulation system of a vehicle, which extends along a longitudinal axis (L-L) positionable in the vehicle in a horizontal position, and comprising: i) a filtration group for filtering the dirty fuel from suspended solids and impurities; ii) a water separation group, for separating the water from the filtered fuel, fluidically connectable and mountable to the filtration group to receive filtered fuel being serially positionable along the longitudinal axis (L-L); wherein the water separation group comprises: - a main body associable to the filtration unit extending along a main axis (X-X) in such a manner that in a configuration in which the separation group is associated to the filtration group, the main axis (X-X) and the longitudinal axis (L-L) are substantially parallel and/or coincident, wherein the main body delimits therein a separation chamber and comprises, at an axial end, an outlet wall on which it comprises at least one outlet mouth from which clean fuel flows; - a separator device accommodated in the separation chamber fluidically connected with the outlet mouth extending in longitudinal direction starting from said outlet wall and comprising a hollow supporting structure, with a clean side fluidically connected with the outlet mouth, said supporting structure comprises at least one passage opening through which the fuel flows, the wherein the separator device comprises a separation surface constituting of a hydrophobic filtering mean which is arranged transversely to such a passage opening; - a blocking device positioned below the separator device dividing the separation chamber in an upper region in which the separator device is accommodated, and a lower region (100"), in which the water separated from the fuel is collected, wherein the blocking device is adapted to prevent the return of water in the upper region comprising a blocking surface extending in a longitudinal direction forming an angle with the direction of the main axis (X-X) which inclines at least a portion of said blocking surface so as to allow the water separated from the fuel to flow towards said outlet wall. i) a filtration group for filtering the dirty fuel from suspended solids and impurities; ii) a water separation group, for separating the water from the filtered fuel, fluidically connectable and mountable to the filtration group to receive filtered fuel being serially positionable along the longitudinal axis (L-L); - a main body associable to the filtration unit extending along a main axis (X-X) in such a manner that in a configuration in which the separation group is associated to the filtration group, the main axis (X-X) and the longitudinal axis (L-L) are substantially parallel and/or coincident, wherein the main body delimits therein a separation chamber and comprises, at an axial end, an outlet wall on which it comprises at least one outlet mouth from which clean fuel flows; - a separator device accommodated in the separation chamber fluidically connected with the outlet mouth extending in longitudinal direction starting from said outlet wall and comprising a hollow supporting structure, with a clean side fluidically connected with the outlet mouth, said supporting structure comprises at least one passage opening through which the fuel flows, the wherein the separator device comprises a separation surface constituting of a hydrophobic filtering mean which is arranged transversely to such a passage opening; - a blocking device positioned below the separator device dividing the separation chamber in an upper region in which the separator device is accommodated, and a lower region (100"), in which the water separated from the fuel is collected, wherein the blocking device is adapted to prevent the return of water in the upper region comprising a blocking surface extending in a longitudinal direction forming an angle with the direction of the main axis (X-X) which inclines at least a portion of said blocking surface so as to allow the water separated from the fuel to flow towards said outlet wall.