I'm getting rear drivers side floor is soaking wet.

I cannot find where the water is coming from.

The inside windows are soaking wet in the mornings as well, I'm sure this is something to do with the carpet being wet.

 

I don't have an answer as to where the water is coming from, but make sure to tilt the rear seats forward and check for water under them. Water collects there in my 2004 XC70 after heavy rainfalls and the soundproofing material soaks it up and holds it. This can lead to mold issues, and possible corrosion in the wiring connections under there. I have to put old towels down and push the soundproofing material into them to get the water out, and then crack open the windows in drier weather to help it all dry out.

 

I have noticed the weatherstripping on the door allows water to get in. I think on the pass side rear door.

 

I had this on my passenger side floor pan. I can't recall if I posted the solution here or not but the AC drain was plugged.
- Pretend that you are going to replace the inside cabin filter - which you may want to anyway.
- Pull back the carpet, it is going to be soaking wet and you have to wrestle with it.
- To the left of the cabin filter compartment and down a bit is a whitish rubber tube connected to a hard white plastic disk that may rotate a little.
- Separate the tube with the connecting disk. This is the drain for the AC unit. It may drain so be prepared.
- Take some leftover weed whacker string - plastic string from a trimmer and thread it down the connecting disk. It will fight with you because the string has to make a 90 degree turn.
- As you push the rigid string through the hole, it will eventually push debris out and below the car. Just keep pushing and pulling so that you are sure the string moves freely.
- Reconnect the drain tube to the connector disk and throw some towels under the carpet and sound foam to try to dry out the cabin.

Button everything back up, and enjoy a good job well done.