A rail vehicle includes a graywater line which is in communication with the surroundings of the rail vehicle directly or by way of a collecting container. The graywater line is equipped with a pressure protection valve, which protects a graywater line section upstream of the pressure protection valve from pressure surges occurring in the surroundings of the rail vehicle. The pressure protection valve is constructed as a pinch valve which is controlled by a control device in order to protect the graywater line section from pressure surges.