I had clear plastic tubing for the fresh water on my boat and I pulled it all out and replaced it all with PEX a few months ago. It is really easy to work with once you buy the crimp tool. It took a couple of hours for the entire job on my boat. I have an on demand pressure water pump in the head, the galley sink is a hand pump and I used PEX for both. I kept a bit of the flexible plastic tubing at the tank and the galley pump to keep the existing fittings.