Welcome to BYC!! :frow We too use the DYI 5-gallon nipple bucket, then keep the coop from freezing in the winter so we don't have to haul water and no open water in the coop either, so bonus!
We've used a 5-gallon DYI bucket with nipples for 7 years. All it took was to get one to do it and never had to worry about it since. You did right to remove all other water and I also did what you did by forcibly showing one. I'd walk away as they will be thirsty, curious, and hit a nipple...