Rear Washer Tubing Leak

It's drain hose or leaking sun roof.

Probably broken fluid hose. Replace same.

Washer pump motor failed

Pull the panel that hoses the motor and arms and replace the hose.

I have the same problem with my 2000 chevy blazer as skornec had posted. I kinda already figured the hose or spray nozzle was plugged. But the problem with checking those items is that I don't know where the hose is located to the back wiper. And the only thing that could be I see that could be the spray nozzle doesn't even have holes that washer fluid could spray from. So basically I just would LOVE if someone could please inform this lame brain of where to find the spray nozzle on the rear window and where in the interior of my blazer does the washer hose run.

There are two screws underneath the window shade pull. You will need a long screw driver to get acess to them after you pull the window shade off. You should have enough access with what you pulled off so far to determine, if there is a plastic hose leak or not without going any farther.

The washer nozzle tip pulls right out of the wiper assembly, with a slight tug from a pair of pliers. But, you first need to unsnap the black plastic nozzle protector. It Lifts up and back toward wiper arm. These are very inexpensive (<$5.00) if you break it. Anyhow, taking out washer nozzle will allow you to determine if there is a clogg causing back pressure on the system wher ethe leaking in the lift gate may be emanating.

check the nozzle by putting a needle into it to make sure it is not clogged up. check hose for leak. pump may not be strong enough to get the fluid there

check in the cargo area of the vehicle, there should be an access panel on either the right or left panel in back. if it has a separate reservoir that's the most probable location
hope this helps

the washer pipe will have blown appart.this happens if you opperate the rear washer when it is frozen.it will either be off in the tailgate usually when this happens there is water around the catch when you open the tailgate.or in the headlining in the left rear,have a feel and see if the headlining is wet.to avoid this reoccuring use a good screenwash with frost protection.

You didn't mention any lost fluids so we can assume that no hapless mechanic has accidentally pulled any tubing loose from the supply. 
If, as in many cars, the path of the tubing connecting the washer fluid bottle to the jets on the cowl are visible, carefully pull one the tubes loose and have someone operate the washer to see if the pump is doing anything any more. You may be able to find the 'Y' junction where the tubes split off to feed the two jets.
The rear window washer has its own fluid supply and pump so is completely independent of the front.
If you find the pump working, then you will have to carefully poke a soft, small gauge wire, preferably copper, to try to clean the jets themselves. You probably have some small bits of something clogging the jets and it can help if someone is keeping the washer pump running while you try to clear them as the pressure will aid you.     
Worst case, the jets can often be replaced fairly easy and at a cost of a few dollars.