A system for disinfecting contaminated water having, in one embodiment, a vessel for contaminated water having an inlet and an outlet. An elongate housing is disposed generally vertically in the vessel, the housing having a housing inlet and a housing outlet, the housing outlet being in open communication with the interior of the vessel. An elongate UV light assembly is disposed in the housing and divides at least a portion of the housing into first and second flow pathways, the second flow pathway being in open communication with the housing outlet. There is a flow inducer aiding flow of at least some of the contaminated water from the vessel, through the housing and out the housing outlet.