Vertical nipples are notorious for doing this....they drip when the chicks drink and they drip if the chicks are wrestling around in there and bump into them. Yet I won't be without them, ever. I've had the open type waterers. I fought the poop and shavings in the water....put it up on bricks, put it up on a bit of 4x4, put it on brinks on a 4x4.....they still got shavings and junk in it, still spilled it, and still managed to soak most of their brooder almost daily. Grrrr So I've decided I'd 10 times rather use a spatula and take out the drippy bedding directly under the hanging waterer than change the entire brooder.
But as soon as I know they are familiar with the mechanism and know how the system works, the pail with the vertical nipples is out of there and they get the big bucket with the horizontal nipples. I've never had a transition issue, and by doing this they are using the same system that the adults use, which is great when they are 4 weeks old and fully integrated with the flock.
But I do understand your frustration!!!
Vertical nipples when they first arrive...
Graduating to horizontal nipples when they can use the vertical ones easily, usually just a couple of days.