Fuel filter system of a fuel system for a combustion engine and method for separating water from fuel

The fuel filtration system (10) has a fuel filter (14) for filtering fuel used for operation of the combustion engine and a water separator (20) for separating water included in the fuel. A connecting pipe (36) diverts to the suction pipe (38) in the water drain pipes (26,28) between the water collection compartment (24) and the cleaning component (32). A bidirectional closable stop valve (44) is controllable depending on the pressure in the water drain pipe such that it closes in case a pressure existing in the water discharge pipe is lower than in the suction pipe (38). An independent claim is also included for a method for the separation of water from the fuel for operating an internal combustion engine.