D.P.
I would try ignoring it. Give her only water since it will dry w/o staining or smelling. Up her solid dairy foods (cheese, yogurt, etc.) to keep her calcium up. When she spits out the water, act as if you didn't see it and don't say a word about it. If she spits it out on the rug or lineolum, wipe it up when she's not looking - wood floor, just drop a dish towel on the ground and push it around w/ your foot. I wouldn't even take the cup away from her when she's spitting - but maybe only put an inch of water in at a time so she'll run out of ammunition sooner. :) Good luck.