Teaching chickens to drink from chicken nipples?

My father and I fashioned a chicken waterer out of a clean five-gallon paint bucket and vertical red chicken nipples. The system works great; there is no leakage, the water stays clean, and it holds a lot more than my other waterers do. The only problem is that my flock literally refuses to drink from it. I've tapped the nipples, held beaks up to it, and even left them without water for a few hours in hopes that they would drink from it. Out of about fifty-five birds, only one will drink from it.
Is there anything else I can try to encourage them to use these? Any help is appreciated, thanks in advance.

Not to worry, this a very popular question and one I had when we first tried the watering nipples.

It's pretty simple...remove all other sources of water and leave them be until they drink. They will eventually figure it out. It might take an hour or 24 hours. Yes, keep flicking the metal thing to release some water and do it in front of a chicken. Then let them be. Thirst will drive them to drink. They're smarter than folks give them credit for. Once one figures it out, another will learn from that chicken and so on.

Don't leave them any other water source and keep them cooped up with the new watering system (if you typically let them free range). If you leave them any other water source, they will be creatures of habit and won't learn the new water source. Keeping them cooped up will not only reduce their activity (and need for water) but will also eliminate the chance that they have a secret watering hole you don't know about!

Folks get worried that their chickens aren't getting enough water when they first try the nipples. They probably aren't, that is, until they figure the nipples out, but they aren't going to die unless you're in the Mojave desert or something like that. A little temporary dehydration won't hurt them, but will motivate them to find water.

It was a warm day, 85F or so, when I first tried out the nipples and it took them about 3 hours before the first chicken figured it out and it was until the next day before I had confirmed all of them were using the nipples. It pained me a little to see them without knowing how to access the water, but like I said, I think they were actually just fine, only a little thirsty for a bit.

If it's cooler now (I just passed through Idaho and it wasn't overly warm there), it will probably take them longer to figure out the nipples simply because they aren't as thirsty.

It also takes longer for adult birds to learn. All the chicks we've raised have figured it out within 30 minutes.

I don't know about chickens, but humans can live for several days without water, perhaps more than a week under ideal conditions. Of course it's not great, but people recover from dehydration all the time. If your chickens haven't figured it out within 24-36 hours (having it be the ONLY water source), perhaps you might consider trying again at another time and for now go back to old water system.