Very late to the party as I have just collected my new Cali and to my disappointment have noticed it has 04S bellows but grey on outside and cream on inside. I have not tested the bellows in the rain but will do so. I notice “Adrian” is mentioned in this thread. Apologies for my newbie inexperience but who is Adrian? It does sound from reading the thread and others on this subject that there is potentially a serious design fault with the bellows. As such they could be designated as “not fit for purpose” and as such my understanding of UK law is that VW have no choice but to replace them, preferably via a Vehicle Recall procedure.
Adrian was the person within the VW UK Executive Office who was handling complaints about the leaking bellows. He has since retired and Rhiannon has taken over this responsibility.
My understanding though is that if you find your bellows do leak, then the 1st port of call should be your dealer.
From reading numerous posts on the forum it would seem that some dealers are happy to accept photo/video evidence of the leaks and will submit a warranty claim to VW based on the evidence provided.
Others will insist you take the Cali to them for tem to carry out their own leak test.
The failures are well known so if you do have a leaking set, there "shouldn't" be any issues in getting them replaced.
I would suggest you test them ASAP by leaving them open in a decent downpour with light winds blowing the rain onto the front and side panels. Or by drizzling a continuous mist of water on them from a hose pipe fitted with an adjustable spay gun.
With my 04S bellows, the areas that leaked were the horizontal and curved seams around the window zips on the front and side panels and the vertical seams joining the side panels to the front and rear panels. Look closely at these areas when you do your testing, but check the rest of the seams/joins as well.
If you are unhappy with them, you could even consider rejecting the van completely, which other have done. The sooner you reach this decision the better. I can't remember what the rules are on rejection but someone may be able to chip in and help.
If you have read through the posts on leaking bellows, you may have picked up that I had one of the early vans with factory fitted 04S bellows and decided to apply Aquatex to stop the leaks rather than opting for replacements at the time. This on the basis that I had little confidence in the replacements being any better. As we are now on version 06S, I think I made the correct decision. Should they start leaking badly before the warranty runs out, I will push for a replacement when the time comes.
In my case, VW wouldn't officially sanction the use of Aquatex, but neither did they say that any subsequent warranty would be rejected.