Hi team, 

I've been struggling to diagnose this on my wife's car and she couldn't possibly tell me how long its been an issue... 🤪

No water is coming out of the rear washer on my mk3 Galaxy (2017).  The pump is working - or at least I can hear it making a noise!  The reservoir is full to the brim and the front washer is working fine. There is no water pooling anywhere else that I have yet identified.  I have pulled the rear high central light off and the washer jet is not blocked (took it off completely and no water came from the rubber pipe).  I pulled the grommet from the boot lid to the body and can't see a kink/breakage (or any one way valve that I have read about).  I then pulled the rubber weather seal off and looked in the headlining and can see the pipe heading forward towards the front right side of the car... No issues evident. 

So. Now I'm a little stuck. I'm going to guess nothing is broken in the cabin of the car as why would it be... and I assume I'd see water.  So I need to move to the front next...  How do I access the washer tank? Is it behind the front right wheel arch?  Please tell me it is easy to access!! 

Thanks. 

Fixed it! 

For future searchers... 

I went to the front of the car and took the front right wheel off. The washer bottle is just in front of the arch liner.  If you remove 5 x 8mm hex screws from the arch and then 3 from underneath immediately in front you can pull/fold back the liner to reveal the back of the bottle including the pump.  If you pull the pipe off the pump you can confirm it sprays with a helper in the car (the pump will dribble out at rest but is vigorous and undeniable if it is spraying. Mine was. 

Now cross, I went back to the rear of the car and started pulling the damn pipe out completely - removed from the rear central light, threaded through boot top and the rubber flex grommet. Then a tiny hard plastic join was found under a piece of tape - this must be the legendary 'one way valve'. It was approx 15mm long and well hidden.  I broke the effin thing removing it so just chopped the last 8 inches of pipe off and stole some from inside the roof liner - loads of extra slack in there. Put it all back together and SUCCESS. Only took me several hours of work (mostly faffing) and more of research.  Doing it again I guess I would have known what to look for and probably got it done in under 30 mins.  

Last job is to clean my roof liner as I didn't have as clean hands as I would have wished and the lovely white is now not quite so...