Wine into water

Practice this before demonstrating!

1. Put some iodine solution (like povidone-iodine solution from a drugstore) into water and call it wine.
2. Put some bleach into a glass of water and call it water.
3. Pour the wine slowly into the water. Don't let the observer get too close or they will smell the bleach.
4. The chlorine is more active than iodine and replaces it causing the color to be lost. Chlorine in the bleach will also remove blood stains, but may decolorize the fabric too.