I had been having problems with my washer jets blocking up and the washer water smelling bad recently  . 
 So yesterday  I decided to investigate looking at the manuel it spoke of taking the front bumper off to get to the washer bottle so I had been putting it off for ages .
 But if the bottle does not need to be taken out its a simple job after taking the grille off ,you can reach the pump etc no problem .
I pulled the pump out of the bottle and found the inlet a bit blocked with slimey build up  :-/ I then found that the rubber mount the pump fits in too is actually a filter which was also blocked partialyso had that out and cleaned it . 
 Another thing I found out was that there is a low level warning sensor in the side of the bottle which was not working so pulled this out too cleaned it up gave it a tap or too and it started working again suspect the contacts had stuck . 
While the pump and switch were out I flushed the bottle with clean water to remove anything left in there . 
Put it all back together and refilled .
I added half of a sterilising tablet in to the bottle to give it a bit of a clean .
Result the washer jets seem much stronger and hopefully wont keep blocking up ,oh and the nasty smell  has gone too  
