So does anyone know whether what Migiwa said about water is true? Asking for a friend
Migiwa is implied to have used waterboarding to interrogate the cultists. Waterboarding, by the way, is a type of torture the US government has defended as an "
enhanced interrogation technique".
Is it true that it makes no mess, and requires no special preparation? Possibly. Is it true that it leaves no wounds? Well, if by wounds we mean external injuries, then not necessarily. But it can cause internal damage. Water in the lungs can lead to infection (e.g. pneumonia), and depriving the body of oxygen can lead to organ damage through hypoxia. The psychological stress on the short term can trigger a heart attack in someone with a heart condition, and even cause damage to a previously healthy heart.
And finally, is it true that waterboarding is a reliable way to "get people to tell you something"? Strictly speaking, yes, it does get the victims talking. But whether the interrogation results in useful information is a different matter. There's
an r/askscience thread on the effectiveness of torture, with links to sources.