I will betcha anything your problem is that it's hanging, and swings when they bump it. Put it on a cinderblock or whatever, with the hanging chain slightly loose (so it's just preventing the waterer from getting actually knocked *over*), and that is likely to fix the problem altogether.
If it doesn't, if you have one of those occasional "really messy drinker" chickens, put the cinderblock on which the waterer sits into a shallow pan or tray; that will prevent the water and wet bedding from spreading across the floor, and you can just change it out every now and then if it seems to be getting ucky.
GOod luck, have fun,
Pat