A sump of a water coalescing filter includes a sump space, a drain coupled to the sump space, a water sensor coupled to the sump space to periodically activate the drain and at least one UVC light source illuminating the water sensor within the sump space. An anti-biofouling reservoir for an industrial fluid includes a reservoir space and sterilization zone or sump space as a lower portion thereof, and preferably a drain is coupled to the sterilization zone, a water sensor coupled to the sterilization zone that is used to periodically activate the drain and at least one UVC light source illuminating the fluid within the sterilization zone. An anti-biofouling water in fuel sensor includes a sensor body having a pair of spaced probes and at least one UVC light source configured for illuminating the probes.