I did a search and did not find anything on this subject. I thought it would be good to share some ideas and tips, and open the topic for discussion. I am a fan of the new PEX waterline. Its supposed to be good to 50 degrees below and I have yet to see a failure. Though I would still winterize it. I personally like "flair-it" fittings. They need no special tools and are trouble free from my experience. There are o-ring style fittings available too but ive had issues with these in the past. I think the tubing nicks the oring on insertion on occasion. I would consider a complete replumb with this material if I had issues with my present system. Now for the different types:
Copper: generally found with soldered, flared or possibly compression fittings. These systems unwinterized are good for a mild freeze or two, then they split. If you want that good old RV look to your plumbing, I would stay with copper and flare fittings for ease of install. Repair:
1. If its flare or compression fittings on the system then i would replace the damaged line.
2. The soldered line is more difficult. You can resolder in a line but that can put a torch flame close to wood. You can hammer the split shut and "sil floss" silver solder the line shut but that requires tools and technique too...and you still have access issues with a flame. Ive had success with using q'est fittings. Since the line is expanded and standard fittings dont work, i cut out the split area and drill out the q'est nuts to allow the oversized tubing to fit. Then I get rubber cones instead of the q'est cones and use them inplace so they fit over the expanded line. These q'est fittings allow all different types of plumbing to be mated. Then i pressure up the system to test. After the third split is discovered..i realize i should have just replumbed...
CPVC: off white pvc appearance with orange glue joints, is the cheapest plumbing available. Very easy to cut and glue. Unwinterized, one freeze will decimate quite a bit of plumbing generally. It splits like bamboo the entire length, right through fittings. Repair:
1. Cut out the bad and glue in fresh...test
Polybutylene: grey or black tubing. The black never gave me as much trouble. The grey, especially with the grey plastic fittings is terrible. The copper fittings are not so bad. Breaks at fittings or splits. Repair:
1. Cut out bad and replace with flair-it and PEX
PEX polyethylene x-linked(crosslinked) white blue or red semiridged tubing. This is the stuff found in all the new coaches and has held up well. Repair same as Polybutylene.