An 
oxygen containing gas is injected at a pressure in the range of about two (2) to about five (5) atmospheres or more into an 
ultraviolet transmissive sleeve surrounding an 
ultraviolet lamp to produce a 
high concentration of 
ozone. Simultaneously, the 
ultraviolet lamp irradiates water to be purified disposed in a container surrounding the sleeve. The 
ozone enriched gas is entrained into the water flowing into the container resulting in an oxidative reaction with any 
organic matter present and coming into contact with the 
ozone. Alternatively, the ozone may be entrained in water in a second container downstream of the container wherein the water has been irradiated with 
ultraviolet radiation. In a further variant, the ozone may be entrained in water in a container upstream of the container wherein the water has been irradiated with 
ultraviolet radiation. In a yet further variant, the ozone may be entrained in one or more containers upstream and prior to 
irradiation of the water with 
ultraviolet radiation in the downstream most container. The ozone may be extracted from the ozonated water prior to 
discharge if the oxidative effect of the ozone is not desired for the intended end use. To enhance ozone production a predetermined pressure is maintained within the sleeve. To prevent damage to sleeve in the event of a drop in pressure of the water surrounding the sleeve, a further 
differential pressure regulator may be used to relieve the pressure within the sleeve by discharging ozonated gas from within the sleeve. By use of specifically configured end caps for the sleeve, certain existing water purification systems may be converted to embody the present invention.