Pick a day that's not too hot where you are available to check in, and make that the only water source. I usually give them a bit of time to get thirsty, then pick up whatever chicks are easy to handle and use their beak to toggle the nipple, letting them drink a few drops, and repeat, and go to the next chick. If they're really hard to catch you can also try tapping the nipples with a finger while they're standing around watching, and the water droplets should help lure them in.I hope to introduce them to the horizontal nipple waterer out there.