The present disclosure relates to a biocide generating system for inhibiting bio-fouling within a water system of a watercraft. The water system is configured to draw water from a body of water on which the watercraft is supported. The biocide generating system includes an electrode arrangement adapted to be incorporated as part of an electrolytic cell through which the water of the water system flows. The water system is configured such that biocide treated water also flows to one or more components of the water system that are positioned upstream of the electrode arrangement.