1) A steady drip of water to the head which turned the victim insane.
2) The victim is placed on a rack horizontally above quickly-growing bamboo shoots, which are watered. The shoots peirce the victim, resulting in a slow and painful death.
3) The victim is force-fed bamboo shoots and water until he cannot take in any more. The bamboo grows inside the victim, until it protrudes from the skin.
4) The victim is force-fed water until he drowns internally.
eg. 2) guy #1 "something smells like toilet water!" guy #2 "yeah, i just gave megan the chinese water torture!"