As we said before, your body will dehydrate much quicker at altitude than it will at sea level.
Having re-hydration tablets with you is going to be extremely important!  As we said before, your body will dehydrate much quicker at altitude than it will at sea level.  Not only should you make sure you are staying well hydrated with 4-5 liters a day, but some days, you may also need to take extra re-hydration tablets.  Depending on where you live, you would want to bring dioralyte sachets, Nuun tablets or whatever you can find locally!