The effect of UV light on bacteria, viruses, spores and moulds has been known to science for many years. Ultraviolet energy at 254nm wavelength is radiated by special lamps. The shortwave ultraviolet energy is lethal to micro-organisms. The ultraviolet rays penetrate the cell membranes and destroy the DNA inside the cell, effectively destroying the organism and its ability to reproduce. Ultraviolet disinfection is extremely fast, it requires no chemicals or additives and cannot be overdosed. No chemical residuals are left in the treated water.