I and several other listmembers have asked over the last year or so if anyone knows where to get a replacement screw-on drain cap for the fresh water tank that provides water to the sink in the westy.  It seems like nobody knew of a suitable cheap substitute that actually fits or was able to find one from any of the normal vendors.  My local VW dealer tracked some down in a warehouse somewhere and said he could order it for $30 or so, but I passed on that offer.  It seems like our friends at Bus Depot acquired some recently and they are now available for ordering on their website.  I got mine the other day and while it was still pricey at $15 or so, it was a lot cheaper than the VW place and seems to be of much better quality and should last a lot longer than the original plastic one that seems to eventually crack for most people.  The Bus Depot web site has two different ones depending on the year of your westy, so be sure to order the right on if you want to get one from them.   It's in the camper sink/water part section of their website.  I didn't know that there were two different sizes, so that might be why some listmember suggestions on this simple part didn't seem to work for me and others.