I agree with extreeme and my water carriage for cooma was 115l of potable in the trailer (60l drum, 20l Jerry 20l square drum and a milkcrate full of 600ml bottles) and 40l in the car (20l jerry 2x4l plastic bottles and 4x 600ml bottles)
The trailer setup is done so that hoses can be used to syphon drain into the kitchenette setup from 1 20l jerry on the top and then fill it from the bigger drum)
used only for drinking water and cooking (dont forget we also had coke and other purchased drinks) me and dad pretty much emptied the 60l drum and 1/2 the waterbottles in the 4 days we were there but we werent exactly practicing good water discipline.

