When we were stupid beginners, and listened to all the "experts", we were almost tossed out of our County Show for putting 7Up in our calves' water. Make sure to read your rules very closely. Many shows have a wording that a calf cannot be fed anything "not Normally" consumed by said animal. This would include, KoolAid, Gator Aid, etc.
Our barn has always been supplied by City Water which was chlorinated. We always kept some Chlorine tablets in the showbox, and added to any water that was not already chlorinated. The best suggestion is to have your calves used to drinking out of a bucket. Once a calf has gone to 5-10 shows, you usually don't have to worry about a thing.