To help keep the shavings out of the water (and feed), raise the waterer until it is about even with their backs, then keep raising it as they get bigger. You can use 2x4 blocks or anything else that is flat.
If they still can fling litter into the water, put it on a platform with blocks so they can hop up to get to the water.
If they still can fling litter into the water, put it on a platform with blocks so they can hop up to get to the water.