Feet in water is not going to make them sick, getting totally wet will give them a chill, which will kill them if not able to get into a warm space.Sadly one of them died, i came back to him being unresponsive on the floor. tried everything I could and nothing helped, I think he had some disease, because if his feet got in the water. he would become sick.
What is the temperature of the brooder at floor level? Do they have a 'cooler' and a 'warm' ends to the broader?