They need about 90 degrees F the first week, dropping about 5 degrees a week after that.
They need clean water to drink, it can be trouble if the water is deep enough to swim in, because their oils and feathers are not ready, so they don't float easily. They can perish in water that is too deep.
Some of us use margarine / cottage cheese tubs with a hole cut in the lid so they can dip their heads in the water but not get into the water. This way they can keep their eyes and nostrils clean, avoiding a number of illnesses.
So try a search on duck brooder on byc. We have some good recent discussions on them.
A gallon chick waterer works fine. It is deep enough so they can submerge their beaks. Since the duckligns didnt hatch out under a hen, they dont have the oils from her, and shouldnt be allowed to swim until at least 2-3 weeks old.