Burmation usually happens during the colder months, however it can be different for every dragon. 
 Usually the signs of this are not wanting to eat, being lethargic, sleeping/napping all the time. 

Its greatly advised you take your beardie to a vet before you stop feeding him and let him do his own thing, this is because he may have pinworms or another internal parasite that has been feeding off the food in his digestive tract, when they stop eating the parasites then eat on their fat stores that help them get through the winter.

Always make sure your beardie goes to the bathroom before going into burmation or the food can rot in their stomach. 

For water you can drip it onto their nose when you see them somewhat awake. And then once a week or twice every two weeks take them out for bath. Make sure they dont drown. Make sure the water is lukewarm, bathe them for 15-20 minutes. 
For beardies not in burmation drip water on their nose everyday, and bath them three times a week.