A water sanitizing system including a supply system having a supply conduit with a conduit length a light-diffusing optical fiber in the conduit that substantially spans the conduit length and an ultraviolet light source configured to inject ultraviolet light rays into the fiber. The fiber includes: (a) a first end and a second end, the ends defining a fiber length, (b) a core region comprising fused silica having a plurality of scattering sites, and (c) a cladding over the core region, the cladding having an outer photocatalyst region doped with a metal oxide. The cladding may comprise a polymer coating. The fiber is configured to propagate the light rays from the first end toward the second end of the fiber, and scatter the rays in substantially radial directions out of the core region of the fiber at the plurality of scattering sites, and through the photocatalyst region.
