I posted a few weeks ago about my coolant level constantly going down
but no leaks that I could see. Thank you to everyone that responded.

Here is what was happening:

There is a bleed screw in the heater under the back seat. This was
leaking. The heater sits in a well and has a wooden cover so when it
leaked it didn't show under the seat. The coolant was running under the
carpet and soaking into it. I never noticed this because I have a rubber
bottomed rug in the back. The other day the carpet must have got to
saturation point because the coolant started running out of the bottom
of the van.

It was coming out in lots of places, I am assuming it got into some box
sections and that was dispersing it around the underside. A $2 part from
the local VW dealer and it's all fixed. That's if it doesn't find a new
way out now. 

Melvin