Chinese Water Torture is in the best cases extremely effective and in the worst cases useless against Humans. It's debatable.
Unsurprisingly Aliens of all species are not familiar with it and subsequently belong to the first Category. -- Anon Guest
One drop... falls. It lands on the brow of the captive, who cannot escape its icy touch. One drop of water is no physical harm to anyone. Theoretically, they could eventually fill the room, were it not well drained. Some drops don't even make it as far as the drains, evaporating from the captive's skin and hair.
Another drop, and another, and another, raining down in slow and steady beats. It's the kind of force that wears holes into stones. It's the kind of force that wears away mountains. It is the relentless force that could tunnel through to the centre of the world, should nothing else stop it.
But it is a single drop of water. There's no way that one drop could hurt or harm a living being. After the third hour of one drop after another, that truth seems less and less likely. Every drop is like a bullet. Time ticks away, and the captive starts to dread the next drop.