Like many other forms of torture, waterboarding doesn’t get any easier with repeated exposure. After multiple sessions of the simulated drowning technique, accused al-Qaeda plotters Khalid Sheikh Mohammed and Abu Zubaydah would at best have been able to slightly modify their response, explains Brian Palmer in Slate. The experience still would have been continually painful and stressful.
Ingesting large amounts of water causes the victim’s intestines to swell painfully; over time, the intestines stretch, which could delay the discomfort a bit—or just lead the interrogator to use more water. Being deprived of oxygen leads to bloated organs and bleeding ears, as well as the involuntary production of stress hormones that can cause asthma and a racing heart.