If there isn't a damp patch in the boot by the lock, the other common place for the rear washer jet to disconnect is in the rear quarter panel (N/S). My washer jet went in both places a few weeks ago. Didn't take long to fix - 10 mins max.
You'll need to remove the headliner near the boot (trim just pops off without too much hassle and can be pulled down rather than removing the whole thing). Towards the left hand side by the rear quarter panel is a 90 degree plastic clip - I think you'll find it has come loose there perhaps? If it has, check in the cubby hole in the boot (where the firs aid kit lives) as there is a recess in there where washer fluid collected in my car. Youll need to dry this out too!
Hopes this makes sense?!