This happened with me once too.  I decided to block the city water line at
the faucet, with Right Stuff, the rubber calk.
I think, probably the aged faucet is crumbling inside and if there is a wall
between the two chambers that is broken, it lets water from one side to the
other.
I don't use the city water side either, because of the same reason.  Leaving
a camper under the pressure of the city water would result in a flooded van
when I come back, or it would happen while I sleep.  Not good.
Took the faucet out by unscrewing the three screws that hold it in place,
then after I lifted it out, took off the grey city water hose, filled the
top end with Right Stuff and installed it back on, then put the faucet back
to it's place.  It worked.
Zoltan

----- Original Message -----
From: "turbowesty" <turbowesty@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, October 11, 2011 2:31 PM
Subject: Water Coming Out of City Water Port

I'm not sure exactly when it happened (either this past weekend or the
previous weekend at Buses of Bon Echo) however I now have a situation where
water comes out of the city water port whenever I use the sink. Water still
comes from the holding tank, it just doesn't all make it to the sink. I
haven't checked to see if it's on the way to the sink or if it's flowing
back and out. I'm just beginning to look through my Bentley, thought I'd ask
here on the list at the same time.

I'm wondering what might have triggered this to happen and suggestions on
where to look to fix it. I never use that port anyhow so I think I'll remove
it over the winter (perhaps add a cooling fan along the lines of what Al
Bell has done).

Regards, Peter Kraiker
nextchapter.kraikerphoto.com
Toronto, ON, Canada
'82 L Westfalia 1.9 TD 5 Spd (Babe)