When you place water under a carpet, it destroys it.
What I expected to happen was...:
It wouldn't destroy the carpet.
What actually happened was...:
It destroyed the carpet.
Steps to Reproduce:
1. Make a 2 blocks long x 1 block deep hole. (make sure it is horizontal)
2. Fill it full with water.
3. Place a carpet on one of the water "block".
4. Stand in the uncovered hole.
5. Fill the below of the covered hole with water.
6. The carpet will get destroyed.