In common with quite a few other people on this site,I found a large puddle in the rear near side footwell. I have read that it's necessary to remove carpets and underlay and hang on the line to dry. I didn't fancy that.

Instead, I mopped up the excess with a load of kitchen Towel, then opened the sun roof and rear windows, put the heating on full pointing down and drove gently around the country side for about 5 hours listening to the radio and relaxing. Result, a bone dry carpet. Now I have to find out how the rain gets into a parked car before the next storm!

if you do a seach for wet carpets i'm sure there are a few threads that deal with "how"