Mine figured out the nipple system within about ten minutes, just from me tapping on the nipple and them watching water drip from it in response. They prefer a trough-style waterer... I have both available to them, since I'm adding electrolytes to their water in the current heat. I only add those to the trough waterer, to avoid any risk of gumming up the nipple tank, and so that they have a choice. They're not as fond of the nipple tank... but if they're thirsty enough, they use it. I can't tell you how to get them to use it, since mine didn't need much convincing - but if they know there's water there, and they're thirsty enough, they should figure it out.