Probably one of the best ways to deal with this, especially with the hose, is just stick with him. Spray him or brush him, and follow him, just keep on doing what you're doing, and when he stops his feet, stop spraying/brushing and praise him. He'll get the idea that the quickest way to be done with whatever it is is to stand still. Works well for fly spray, too. Stopped feet alone is a fine goal in the beginning, but as he does that consistently you can wait for him to relax as well before removing the "pressure."
If this is a recent development, I would also suggest looking into any physical cause for the antsyness. If he's tender somewhere, that could definitely get him stepping away from a brush or a hose spray. The process above will help with a training issue, but won't be helpful if he hurts.
A stubborn horse walks behind you, an impatient one in front of you, but a noble companion walks beside you ~ Unknown