The UV Stage of your water cooler has caps on either end of the housing that can be screwed off to replace the UV bulb. Inside is a quartz sleeve that is sealed with o-rings on either end by the caps. If you notice leaking, you may need to replace the O-rings.
Set of 2 O-Rings for UV Bulb Housing – ORNG-1014
Set of 2 O-rings for UV housing in Vertex PureWaterCoolers.