In article , Howard Goldstein wrote:

Some of the pipes are outdoors though and the CPVC manufacturer
recommends shielding them from UV to avoid brittleness. A "water
based paint" of some unspecified type is an allowable covering.

Any outdoor LATEX paint is water based. Benjamin Moore makes a good
paint. Unless you have a huge amount of above ground pipes, you'll
probably get away with just a quart of paint and a quart of primer.
Pick a dark color - it cuts down on UV better.