A fuel filtration and separation assembly of a fuel circulation system of a vehicle, comprising: i) an assembly casing which extends along a longitudinal axis (L-L) positionable in the vehicle substantially in a horizontal position, fluidically connected with the fuel circulation system, comprising an inlet wall comprising at least one inlet mouth and an outlet wall comprising at least one outlet mouth; ii) a filtration group for filtering the dirty fuel from suspended solid particles and impurities, housed in said assembly casing in fluidic connection with the inlet mouth; iii) a water separation group, for separating the water from the filtered fuel, housed in said assembly casing in fluidic connection with the filtration group and with the outlet mouth and extends along a main axis (X-X) in such a way that the main axis (X-X) and the longitudinal axis (L-L) are substantially parallel and/or coincident; wherein the water separation group defines a water separation chamber, comprising: - a separator device housed in the separation chamber fluidically connected with the outlet mouth extending in longitudinal direction starting from said outlet wall - a blocking device positioned below the separator device dividing the separation chamber in an upper region wherein the separator device is housed, and a lower region (100"), wherein the water separated from the fuel is collected, characterised in that the separator device comprises 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, wherein the separator device comprises a separation surface constituted of a hydrophobic filtering means arranged transversely to such passage opening; and 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) an assembly casing which extends along a longitudinal axis (L-L) positionable in the vehicle substantially in a horizontal position, fluidically connected with the fuel circulation system, comprising an inlet wall comprising at least one inlet mouth and an outlet wall comprising at least one outlet mouth; ii) a filtration group for filtering the dirty fuel from suspended solid particles and impurities, housed in said assembly casing in fluidic connection with the inlet mouth; iii) a water separation group, for separating the water from the filtered fuel, housed in said assembly casing in fluidic connection with the filtration group and with the outlet mouth and extends along a main axis (X-X) in such a way that the main axis (X-X) and the longitudinal axis (L-L) are substantially parallel and/or coincident; wherein the water separation group defines a water separation chamber, comprising: - a separator device housed in the separation chamber fluidically connected with the outlet mouth extending in longitudinal direction starting from said outlet wall - a blocking device positioned below the separator device dividing the separation chamber in an upper region wherein the separator device is housed, and a lower region (100"), wherein the water separated from the fuel is collected, - a separator device housed in the separation chamber fluidically connected with the outlet mouth extending in longitudinal direction starting from said outlet wall - a blocking device positioned below the separator device dividing the separation chamber in an upper region wherein the separator device is housed, and a lower region (100"), wherein the water separated from the fuel is collected, characterised in that the separator device comprises 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, wherein the separator device comprises a separation surface constituted of a hydrophobic filtering means arranged transversely to such passage opening; and 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.