Water in trunk lid liner and rear drivers side passenger floor
 

I saw that there was a similar thread already about there being water in the trunk lid liner, but my water issue has a twist.

I'm getting the water in the trunk lid liner just like the other person described, however there is also water showing up on the rear drivers side floorboard as well as under the seat on the same side. It seems that the small dip under the seat is filling with water, then trickling down to the floorboard. The maddening part is that I have no idea where the water is coming from. Since I live in south Florida, the first time this moisture got inside the heat caused a great deal of condensation within a very short time and ruined the rear windshield tint - but I don't want to replace that window until I've stopped the moisture from entering.

There isn't a Caddy dealer within a two hour driving radius, so "popping over to the dealer" really isn't an option for me. If it's a seal, I'd like to try and take care of it myself.

Are these two linked, or am I just unbelievably unlucky?

Details of car:

2008 CTS - located in south Florida.

Thanks in advance for any help or suggestions!

You have a sunroof. Mine is plugged up n need cleaned and in leaks front driver side floor n in the trunk.

Exactly what Don said. The 08-14 CTS with panoramic sunroof has 4 drainage tubes 2 in front, 2 in back. When they plug, they leak into front floor boards and trunk. My local Caddy dealer said they would clear all four for around $120.00. YouTube it, may be able to do it yourself. I heard you may be able to clear the fronts with air, but I am nervous about that. My front passenger is plugged tight. If you open the sunroof, you can see the drains with a flashlight in the corners, and they may be plugged on top as well.

After YouTubing and talking to a friend that works at the Cadillac dealership here, he suggested blowing out the front tubes with air pressure (you can't access the rear tubes this way). First I poured a cup of warm soapy water into the sunroof track. I used a poly 1/4" tube, pushed it against the corner drain hole and held my air gun nozzle against the other side. It blew clear immediately! Then I poured a couple more cups of warm water through and it poured out behind the front tire as it is supposed too. Saved 120 bucks!

I had the same issue with an 09 CTS, water would drain back and leak inside the trunk, and other areas as mentioned. I took the following steps to correct it:

Removed sunroof glass (both) and replaced seal ($160 at dealer)
Lowered headliner, removed sun roof drain hoses at bottom ends and cut nipple holes a little bigger, used cotton tips to clean mud and dirt from nipples, hoses were clean.
I tested the drainage before reassembling it all together, by running water on the channel bellow the sunroof opening.
when I bought it, this car's trunk was full of water and water would pour from the front buttons on the light and sunroof control area.
After the work mentioned, all leaks were corrected.
about 10 - 15 hours of work, I looked it all up on youtube, I had never worked on a car before, ever.
Feel pretty good about the results.
Good luck!!!