Synonyms for Outflow (same or very similar meaning)
WordNet sense 1 (the process of flowing out):
effluence, effluxWordNet sense 2 (a natural flow of ground water):
fountain, outpouring, spring, natural springWordNet sense 3 (the unwanted discharge of a fluid from some container):
escape, leak, leakageFrom the ODE community, based on WordNetadd/edit