The "how much to carry" is a loaded query -- ask 10 people and you will get 20 answers.
The last time that I gave my amount, someone else did the "are you nuts" routine, so I will refrain.
(HI, are you nuts?)
Even if you are a camel -- like HI -- I would still carry some water for First Aid purposes, ie, something in the eye needs to be washed out, a scrape needs to be cleaned, a sudden bum knee turns what should be the 'planned' amount of time up/bsck to refill.... into thirsty hours..hours..hours..
