Water supply device for a rail vehicle, comprising: - at least one fresh-water region having - at least one fresh-water tank, - at least one fresh-water discharge point, and - a fresh-water supply line between the at least one fresh-water tank and the at least one fresh-water discharge point, - at least one grey-water region having - at least one grey-water feed point, - at least one treatment apparatus for grey water, comprising - a grey-water container, - a grey-water inflow in an inlet region of the grey-water container, - an outflow for treated grey water in an outlet region of the grey-water container, - at least one filter between the inlet region and the outlet region of the grey-water container, - a fresh-water inflow for the supply of fresh water, which is arranged in the outlet region of the grey-water container of the treatment apparatus for grey water and which is connected via a fresh-water supply line to the at least one fresh-water tank, - at least one discharge point for treated grey water, - a grey-water supply line between the at least one grey-water feed point and the grey-water inflow in the inlet region of the grey-water container of the treatment apparatus for grey water, and - a supply line for processed grey water between the outflow for treated grey water in the outlet region of the grey-water container of the treatment apparatus for grey water and the at least one discharge point for treated grey water, characterized in that the at least one filter between the inlet region and the outlet region of the grey-water container of the treatment apparatus for grey water is a gate filter. - at least one fresh-water region having - at least one fresh-water tank, - at least one fresh-water discharge point, and - a fresh-water supply line between the at least one fresh-water tank and the at least one fresh-water discharge point, - at least one fresh-water tank, - at least one fresh-water discharge point, and - a fresh-water supply line between the at least one fresh-water tank and the at least one fresh-water discharge point, - at least one grey-water region having - at least one grey-water feed point, - at least one treatment apparatus for grey water, comprising - a grey-water container, - a grey-water inflow in an inlet region of the grey-water container, - an outflow for treated grey water in an outlet region of the grey-water container, - at least one filter between the inlet region and the outlet region of the grey-water container, - a fresh-water inflow for the supply of fresh water, which is arranged in the outlet region of the grey-water container of the treatment apparatus for grey water and which is connected via a fresh-water supply line to the at least one fresh-water tank, - at least one discharge point for treated grey water, - a grey-water supply line between the at least one grey-water feed point and the grey-water inflow in the inlet region of the grey-water container of the treatment apparatus for grey water, and - a supply line for processed grey water between the outflow for treated grey water in the outlet region of the grey-water container of the treatment apparatus for grey water and the at least one discharge point for treated grey water, characterized in that the at least one filter between the inlet region and the outlet region of the grey-water container of the treatment apparatus for grey water is a gate filter. - at least one grey-water feed point, - at least one treatment apparatus for grey water, comprising - a grey-water container, - a grey-water inflow in an inlet region of the grey-water container, - an outflow for treated grey water in an outlet region of the grey-water container, - at least one filter between the inlet region and the outlet region of the grey-water container, - a fresh-water inflow for the supply of fresh water, which is arranged in the outlet region of the grey-water container of the treatment apparatus for grey water and which is connected via a fresh-water supply line to the at least one fresh-water tank, - a grey-water container, - a grey-water inflow in an inlet region of the grey-water container, - an outflow for treated grey water in an outlet region of the grey-water container, - at least one filter between the inlet region and the outlet region of the grey-water container, - a fresh-water inflow for the supply of fresh water, which is arranged in the outlet region of the grey-water container of the treatment apparatus for grey water and which is connected via a fresh-water supply line to the at least one fresh-water tank, - at least one discharge point for treated grey water, - a grey-water supply line between the at least one grey-water feed point and the grey-water inflow in the inlet region of the grey-water container of the treatment apparatus for grey water, and - a supply line for processed grey water between the outflow for treated grey water in the outlet region of the grey-water container of the treatment apparatus for grey water and the at least one discharge point for treated grey water, characterized in that the at least one filter between the inlet region and the outlet region of the grey-water container of the treatment apparatus for grey water is a gate filter.