A fuel cell system is described that enables discharge of moisture generated by the fuel cell system based on pressure differences between components of the fuel cell system. The fuel cell system includes a fuel cell that discharges oxidant offgas via a cathode discharge pipe and discharges fuel offgas and moisture to an anode drain opening that in turn discharges the fuel offgas and the moisture to a gas-liquid separator via an anode drainpipe. A throttle valve establishes a pressure difference downstream within the anode drainpipe to enable movement of the fuel offgas and the moisture from the anode drain opening to a lower pressure area of the gas-liquid separator. In addition, the pressure difference enables the fuel offgas to flow from the gas-liquid separator to the cathode discharge pipe through the throttle valve.