During routine RV inspections, I often find damaged plumbing vent caps on the plumbing vents. The roof is often neglected during normal use and maintenance. The poor old roof vents are battered by low lying branches and other low hanging objects and are often ripped off the roof or broken to the point that they are no longer functional. The plumbing vents need caps on the vents to keep water and other debris from entering the vent lines and eventually the holding tanks. It is a good idea to climb up the ladder to check the roof for damage on a regular basis. Even if you don’t bother to wash it, which you should, go up to check on the condition of the roof vents and other components attached to the roof.
Roof vent replacement caps are very inexpensive but are still a critical part of the RV plumbing system. Take the time and make sure that yours are still in good shape. If pieces are missing, replace the vent cap.