The water pump on my 3 week old T6.1 Ocean has stopped working, at least there's no water coming out of the tap and doesn't appear to be the previous 'wirring' noise ! Tank is full and tap is on above the gas tank. Has been working OK, going to France on Sunday and dealer can't get me in...
Some have had issues with air locks - have you tried with the water filler cap off? Empty tank and refill?
If not you might have to get your hands dirty and start following the pipes through, starting at your clean water tank (the gas bottle goes inside the tank) and following the pipe through to the tap - you can trace it by emptying the cupboards and looking through to the back shelf.
Worst case is it's working and pumping water into your van somewhere!
Agree with @dspuk, most likely an air lock, especially if the tank has been completely empty and the pump ran dry. Its happened to us. Advice I received and acted upon:
1. Remove water fill cap and try ((tank can pull a vacuum).
2. With tap raised, try to suck the air through.
3. With tap raised, and pump running, try and blow back through the tap/ pipe.
If none of this works, there may be an issue with the pump. Is it a new van? Has the tap been working okay?
I’ve found that if I fill the water tank to overflowing then I have to remove the filler cap before any water will flow. I think the air inlet gets blocked by too high a level.