Hello Ramblinpete. Like you I also own an Alpine 1999 36' MDS that had a fresh water tank leak. On my coach the leak was at the gate valve, which is located in the driver size storage bay. Do a search for gate valve on Am.zon and you will see a good picture of a similar gate valve installed in the 1999 Alpine. To gain access I had to crawl inside of the bay. My valve leaked the entire tank in a 24 hour period. As a quick fix I removed the valve and installed a 2" end cap. In the future I will install a 1/2" PEX pipe from the bottom of the tank with a ball valve and place it near the propane tank. It will be similar to the overflow valve that is installed at the top of the tank, however the future drain valve will be installed at the bottom of the tank.
1999 Alpine Coach MDSS - 2003 GX470 Toad
Roger, Christine, Isabella(7), & Sophia(2)