Your rear window washer fluid comes from that same tank as your front windshield, and then a tube runs to the back of the vehicle.
If you are not getting any fluid on the rear window, could be a plugged hose? You would need to have someone check it out.
〉 Answered on Jan 3rd, 2007 by Amy Mattinat, Owner and Author at Auto Craftsmen Ltd
Check your owners
manual for the location of the water bottle. Most vehicles that have a
rear wiper use the front water bottle under the hood. There is usually
a hose that goes to the back. Sometimes this hose can get clogged and
you may find that even though the front washers work, the rear may not.
If you take it to an ASE certified shop they can clear it sometimes by
blowing compressed air through the hose.
〉 Answered on Dec 15th, 2006 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines
This is usually filled in the same reservior as the front windshield wiper fluid. If the rear does not operate
and the front washer fluid is full, there is a problem with the rear washer
system that requires diagnosis to determine what's going on. Make sure you take it to an ASE certified technician to diagnose it.
You can find one near you by going here: