I use a rubber stopper I got at a wine making supply store.
Edward

At 10:47 PM 10/14/2010, you wrote:
>I've been searching for a substitute for the plug for my water tank
>inlet, and finally found it today: it's 7/8" to 1" "Expand-tite" for
>plugging engine blocks. Fits perfectly, and the "key" is just a nut
>driver.
>
>This is for a 1982 Westy.
>
>Mark