How much do you drink on a ride like this?
Truthfully Mick, this will depend on your body. I'd weigh yourself before you go on a long ride and after you get back. You want to be drinking a litre per pound lost or so. And not just water. Electrolytes are key.
I was out for 3:45 and went through 6 water bottles. I carried three and had to stop once to fill up at a store.