Where to find valves like this?

maillemaker wrote:

Do you really need the drain valve?

Yeah, if you don't drain your water lines in winter things freeze and crack.

Steve

There are other ways of removing the water, depending on low point drains is asking for trouble, but in any case try http://catalog.winnebagoind.com/menu/Parts.htm
Winnebago is very good about stocking obsolete parts for their rigs.