PVC pipe exposed to ultraviolet light for long periods of time loses some strength but rarely enough to cause a significant drop in the material's ability to withstand water pressure. Ultraviolet rays also cause colour changes in the pipe's exterior. You may avoid the problem by painting any PVC pipes in your home directly exposed to the sun with a ultraviolet -resistant paint.
Set up your work area. Work in a well ventilated area. If the pipes can not be moved, open windows and set up fans to circulate the air. Chemicals such as naphtha-based fluid and PVC primer can have adverse effect on users in closed-in areas.
Put on the gloves. Some of the chemicals needed for this process are harmful to skin.
Clean the PVC pipe with the rags and water. Remove all stickers and debris from the pipe. A naphtha-based fluid can be used to remove adhesive and oil from the pipes if necessary. Rinse the pipe off with warm water after any chemicals are used to clean the pipe. Dry the pipe with dry rags or a towel. The pipe must be dry or the primer will not work.
Cover the PVC pipe with PVC primer. Brush the primer over the entire pipe with paint brushes. Allow the primer to dry.
Paint the PVC pipe with water-based latex paint. Use paintbrushes to apply an even coat of the paint. Light colours are preferred in this process because they reflect light and are ultraviolet resistant.