Thanks for all the good ideas, either helpful or not.

As stated, the bike is in pieces in my apartment, I don't have access to a blow torch and I don't have a girl friend.

I had actually hoped that someone knows the internal setup and where to drill a hole so the water can escape. The water probably is trapped in there because of an imperfect weld seam or something like this because only one of the two chambers has the water trapped inside.

Anyway, I don't expect further comments.