Cockatoos actually love baths and will spread their feathers to get a good soak.
However, they need to do it their way and at their time. Most of them will react negatively if you try to force them under the faucet, and may actually become traumatized—not by the water, but by being manhandled. Just hold the hose steady, and give them enough room to get in or out of the water at will.
Since cockatoos are curious and active, they need at least one hour of “free time” outside of the cage each day. The challenge lies in giving them freedom while keeping them out of problem. The solution is a bird-safe room.
The first step is to clear the room of cats and cat paraphernalia. Cats carry the Pasteurella bacteria, which can kill birds. Then, cover or hide electrical wires, which it may decide to turn into chew toys. Hide poisonous items (including some household plants like poinsettia) or human food like chips or chocolate.
You should also keep the cockatoo out of the kitchen and bathroom. It can brush too closely to a boiling pot of soup, or inhale the gases emitted by heated Teflon. It can also drown in a sink or toilet bowl full of water.
Cockatoos have very delicate respiratory systems, so don’t use any aerosol sprays or allow any smoking in their room. .
You should also prevent the cockatoos from escaping. Close all the windows, double check the screens for any holes or loose corners, and hang a “Cockatoo Loose, Please Close the Door”—to remind members of the household. You should also clip the birds’ wings, so just in case they do manage to break free, they can’t fly very far.