All animals need a 24/7 supply of clean, fresh water. Dirty water makes for sick animals, and empty water bowls makes for miserable animals.
Baby goats have a hard time navigating deep water bowls for their first few months, and could even drown if they get in too deep. But after they’re 4-5 months old they should be fine, provided your water bucket isn’t too tall for them to get their heads over.
While you should NEVER put your feed bowls on the ground (where goats will promptly poop into them) it would also be good if you could either elevate your water bowl/buckets above where the goats could poop in them.
Frankly, if your bucket is a foot or so deep, I wouldn’t think your goats would be accidentally backing up and pooping into it so you should be fine. A foot deep, however, is a bit too deep for under 1 year old goats to get too, so you probably should have something shallower (a 6″ deep tub thing?) out there so your youngsters can drink.
Remember that in the winter, you need to keep your water un-frozen… and more than that, you really should keep it un-freezing! And by that I mean that you really should have one of those plug-in heated water buckets. They don’t only keep the water from becoming iced over, they also keep the water temperature up above freezing, to around 50 degrees, in my experience.
Think about it–if it’s 38 degrees and raining out there, even though the water isn’t technically frozen, it’s awfully chilly and your goats will only reluctantly drink such almost-ice-water. Buy a nice heated bucket, and it’ll never freeze, and it will be un-chilled enough so that your goats can stay hydrated even during those almost-freezing nights.