Albanach

On my 2011 A4 Avant the front and rear windscreen spray nozzles constantly block up so I think I need to clean the reservoir out and flush the system. How do I access the drain? Is it behind the liner on the passenger side wheel arch? Or is removing the bottle itself a big job?
Can I put the likes of a full or half tablet of calgon and hot water into the reservoir and leave for 1 hour or so then flush system?
My bottle has no gauze filter at the filler cap so my fear is that the previous owner damaged it and the threads of the gauze are loose inside the reservoir.

SMac770

Don't know about any of the rest of your questions, but the tank is behind the left front wheel well liner in my US spec 2009 A4 Avant. One day, I need to pull that out and find out why it leaks when I fill it up.