An apparatus for the treatment of aliquid that includes a chamber having at least oneinner surface, the chamber adapted for passage ofa fluid therethrough. The chamber is at least 80percent enclosed. The apparatus also includes anoptional ultraviolet-transmissive tube disposedwithin the chamber and also adapted for thepas-sage of the liquid therethrough. The apparatusfurther includes an ultraviolet lamp disposedwithin the chamber and, optionally, within theul-traviolet- transmissive tube. A reflective materialis interposed between the chamber and thetrans-missive tube. The reflective material is adapted soas to reflect at least a portion of light emitted bythe ultraviolet lamp, wherein the reflectivemate-rial is at least 80 percent reflective.
