There is another good thread on this:
I posted a detailed post on my approach here:
http://www.enworld.org/forum/showth...hirst)/page3&p=7074305&viewfull=1#post7074305
The TLDR version:
Fun trumps. Assume the adventurers are the hardy survivalists that they are supposed to be and that they somehow manage when it is not central to the story.
Occasionally, however, it can be fun to have a resource-management challenge, and water is one of them.
Survival skill checks that fail, should not be limited to: you find no water, your are dehydrating. You may find water but not properly boil it and get giardia. Perhaps the only food you find is carion and you get sick from it.
Water is heavy. Anyone who has done seriously long back-packing trecks knows you are not carrying all the water you will need for the entire trip on your back. You need to plan your route around water management concerns. But if that is just going to come down to a DM making your roll a few gratuitous survival rolls, why bother at all. Assume your ranger who is proficient in survival knows his bush skills 101.
More interesting is to have a map. Show where the water is. The streams, area of pasture, lakes. But that is in the low lands. It will take longer and is more dangerous because thats where the orc villages are located and the patrols then to be heaviest. There are some short cuts over rough mountain terrain but water will be harder to come by. Going through a desert? Here is a map with the locations of the oases in the area. Something any caravan leader could sell to the party. But it is also much more likely you will run into adversaries there. It will make it harder for you to sneak through this foreign land to the forbidden temple. How many oases do you risk visiting? How much travel over the desert without replenishing your water supplies will you risk?
Of course, create water is a 1st level cleric spell. So the challenge isn't that difficult to solve, but the cleric will need to prepare that spell over another and will have to use up spell slots to create enough water for the entire party. It would be a pity to be attacked RIGHT after having spent your spell slots on filling water containers. "Sorry, I can't heal you until after a long rest. Uh, have some water?"