Epoxy metering pumps can be left in the containers when not in use for a few weeks, but for longer-term storage, it is better to pull the pumps out, clean them, and put the original caps on the containers (always be sure to put the resin cap on the resin container, and the hardener cap on the hardener container. Hardener pumps can usually be cleaned by cycling warm water or denatured alcohol through, and the resin pumps can be cleaned out with denatured alcohol.