Hi,

I have 1 Camelback (3L), 2 bottles on the bike (1,5L), 2 waterbags (10L) and I'm able to attach 10 PET bottles (20 L). Additional I can carry 10-15 kg fruits - which contain also water.
That should be sufficient to cross the Sahara in summer ;-).
I normally carry 4 L of Coke and 3 L of water for a hot day (>40°C - no shade). That's for me sufficient. If there is no water available than I don't boil water for cooking.

Thomas