[wastedyears]

***If Mohammed faced waterboarding for 90 seconds, Nance said, about 1.2 gallons of water was poured down his nose and throat while he was strapped to a board.***

What’s the capacity of the lungs?

[Joe 6-pack]

Not all of that amount goes into his lungs. Waterboarding works because causes the body to "lock out" the nose and windpipe making breathing just about impossible. The minute the water supply is cut off, the subject is able to breathe again; they don't actually fill the lungs with water (although a small amount might be inhaled). It's the perception that one is drowning...not that one is actually being drowned.