Some embodiments of an infusion pump system may be configured to provide a desired level of resistance to liquid ingress to the pump casing while contemporaneously providing air transmissibility for equalization of air pressure differentials between the interior and exterior of the pump casing. Further, some embodiments can detect when moisture inside a casing of the infusion pump system is greater than or equal to a threshold level and can initiate one or more patient safety countermeasures.
