Is waterboarding torture?

In my opinion, dripping a little water in someones nose is not turture. Chopping off body parts, yes. But water in the nose......c'mon. Plus, it's proven to WORK, i.e Khalid Shaikh Mohammed. And don't say it makes people say anything their captors want to hear, because the captors will always verify the information through other sources. So what do you guys think? It is torture, or an effective interrogation method proven to work, and in the process, save American lives? Why or why not?