A4 1.8T - Water leak

[Tross]

My 2001 A4 1.8T seems to be going through water like it's.....water. Forgive me if I'm being really thick but can't recall having another car go through so much water. I have checked for obvious leaks and there are none and the oil seems fine too. I generally have to fill on a weekly basis. Mileage is 95k - Any ideas ??