I have a 2007 Suburban that everytime we fill the windshield wiper fluid it leaks out the back of the suburban. I can't find the water line in the rear to replace it. I cannot get in water to stay for the back windshield wiper!!

 

Windshield washer line is a very small diameter black hose. Easiest way to find is at the rear driver side corner look directly UP. It has a small plastic fitting to hold two splices of line together and they commonly come apart (I have a 2007 suburban and mine does too).
I'll try to upload a photo showing the line on mine. I wrote some areas of reference to try to help pinpoint what you're seeing.
Make sure that piece is connected (if you're losing the fluid under the rear driver side I'm fairly certain the connector came apart).

Picture underneath rear driver side bumper showing window washer fluid line

Edit: make sure you dont pull the line and disconnect from somewhere else... mine was disconnected behind fuse relay under hood AND under rear bumper area when I got it.

 

Have a rear cargo leak in my Tahoe as well but don't know where it's coming from the headliner towards the back doors are soaked and water has leaked clean through the left rear speaker in the cargo area however the carpet is mainly soaked on the left side and all the way across at the rear doors in the cargo area but after a few days of rain most of the cargoes carpet area are wet I've only had the truck a few months bought it as is from a title loan it has a roof rack and looks like it have an after market roof brake light

 

I have a 2017 Tahoe that just started leaking from the top rear passenger side. Headliner is wet and leaking down onto the vent. Any ideas ? There's some built up crud behind the plastic guard when you let the rear hatch up.

 

A few years back, my '13 Suburban started having the exact same leak you described. If I parked with front slightly downhill hardly ever leaked. But if rear was lower than front, it leaked. I cleaned everything possible around the area, even took out the bolts/screws for the luggage rack and resealed. None of that stopped the leak. The problem turned out to be a rubber boot (there's two boots). one where the wires come out of the body and another where they go into the liftgate. My problem was the boot coming out of the body. Somehow it had came out of position. Any water that goes past that boot goes directly onto the right side of headliner. There a trick or certain way that boot fits into the body, seems like there is a hard insert in boot. I'd bet money that's where your leak is.
You might check U-tube to see how that boot fits. Once the boot is in place...no more leaks.