Sadam Hussein's henchmen were known for water boarding. There are a couple of ways to drown. One is your lungs filling with water depriving the body of oxygen. Another is ingesting (drinking) too much water thush flushing minerals and nutrition from your system. Known to happen during marathons and initiations/contests where large amounts of plain water is ingested. Sadam's henchmen would continue to water board for lengths of time causing the victim to swallow enough water until they would purposely drown them. Describing bellies so swollen that they looked like a watermelon ready to pop.
When done by the Good Knight it is not torture because no purposeful physical harm can come to the victim. Who gets to define the Good Knight?
During WWII it was used by the Evil Empire and known by the Allies as Japanese Water Torture.
After reading some info about it:
To be truly effective you have to have multiple questions to ask.
Convince the victim that they are being water boarded by the Saudis because they think the Americans won't drown them.
First ask questions and get answers before water boarding.
Walk victim into room with about 100 1-gallon jugs of water for him to see.
Second ask questions multiple times during a water boarding period of say 15 minutes.
Let victim recover (vomit and breath) and think it is over then throw his ass back down and do it all over again documenting the answers.
Do this for multiple days and then compare the answers. They say the truth normally comes out during the first session.

I have mixed feelings about the U.S. using these methods. I see a need to get info that can keep us from harm. I always thought we had a good legal system and were a strong nation before we started doing this. We always hated the Russians because they did this.