I have been noticing water on the floor behind the drivers seat underneath the rubber floor mat. I took the car to the dealer and they removed A,B,C and D pillars, cleaned out the sunroof drains and ran a hose on the car and were unable to duplicate the problem. Looking for recommendations to help me try and diagnose this issue. Thanks.

 

I've heard on the older models (C6) that the AC drain line can get clogged and the condensation water drips into the rear foot-well. Have you by any chance been running the AC often?

I can't think of another way to have water in your interior only in a single location. Good luck finding the issue - please post a reply when you do find a fix.

 

Would you happen to know the process on how the clean the AC drain?

 

Unfortunately not. I would use Google. The only thing I came up with where references for other Audi models but I'm sure it will be very similar to your car.

It looks like either AC drain or sunroof drain is your best bet that I can come up with.

 

Problem fixed. The dealer found that the snap ring that holds on the AC condensation house was broken off. Water from the AC was running down the channel on the floor to the back seat. Dealer fixed and removed and dried out the carpet. Another great Audi dealer experiance.