If there isn't a light source they won't move around at night. They will sleep so I would say yes they should be fine. But if you have any lights on they will get up to Drink. Otherwise I wouldn't worry about it as long as their is water available as soon as they wake up as they will be very thirsty.
Theyou will have water sources available for dunking outside during the day. We have a pool for them and I keep buckets around the yard. They might even find the stream behind the house if they ever think to explore! Will they be ok in the coop/run at night without a dunking source?