You're taking things based on best scenarios...

You don't only need to take humidity, air temperature into account, but also how much a person has had to drink already before that person gone into a waterless drought...

3 minutes without air isn't true, people have stayed up to 5 minutes? without air... 3 minutes is probably the limit where an average person would start loosing consciousness and brain damage starts to occur.

I would say two (2) to four (4) days without water, depending on Humidity, Air Temperature, and how much a person has had to drink already...

I would say maybe in the last 12 hours you would lose consciousness and your organs would slowly dry out and die away...

Impossible for a person to live without water. Substitutes also contain water.

In best scenario, high air humidity (around 93%, non-fogging), low air temperature (around 18C), A person who is healthily hydrated, drunken atleast 3.1L of water in the past 24 hours, should live around 3.5 days, or in other words around 84 hours, that is my assumption, so knock yourselves out trying to prove me wrong!

There was a short quip I read years ago in an Analog magazine, semi relevant but funny;

Have you ever seen the show Survivorman or Man vs. Wild? The special need of the body for water comes up often including the additional information that a sufficiently water-saturated plant, if it's a safe plant, can allieviate some of the dehydration. Also interesting about Survivorman is that while the Canadian host is knowledgeble and capable of survival in most any environment, deserts kick his butt. For him it always comes down to not enough water in the environment to avoid dehydration. And that was even in winter when dew pools could be found.

For a real answer check out a first-aid or a 'what to do in an emergency' site.

Wow after reading up on some posts i dont go a day without water.

I def would struggle after one day without water or any sort of drink.

Well, I would say 3 days is the time where you drop dead because let's analyze it logically... Your body is made up of 70% water, you need around 1.5 - 2 liters of water daily, all metabolic reactions in your body require water, all your other body functions require water to be present, your blood is made up mainly of plasma (which is basically water)... so if you do not supply your body with water, soon your body functions will stop, your metabolic activity will cease, your blood pressure will drop, and finally within 3 days maximum you will drop dead lol! So yeah, I believe it's 3 days maximum and 2 weeks is tooooo much!! I strongly doubt that a man can stay alive for 2 weeks without drinking any water!

I was always told that you can live without water for 2 days.
But I began to doubt when I didn't drink anything for almost 2 days and I only had huge headache and felt weak.

So I think you can live 3 days with out water.

I think you can go three days without to the least. Depends in the place your in and the scenario.

in cooler places you could live more in hotter places you go unconscious faster.
2 days without water seems you could even 3-4 ...but that's not for everybody... if you're enough hydrated and stay in a cool enough place not in the sun you could survive more...if not you'll die most probably in the second or the third day.
Also is a sure thing that if you keep thinking about the last time when you drank enough water and you were well hydrated you can fool your senses and think that there is no problem... I don't recommend to try something like this because you can loose your consciousness and you'll be unable to call for help, anyway I daub that is somebody willing to try this

I always found this question quite interesting, so I decided now to do a bit of research by myself.
Most of the answers here seemed a bit speculative, so I thought I should turn to a somehow 'authorized' source.

From wikipedia, a page about survival skills:
'A human can survive a maximum of three days without the intake of water assuming you are at sea level, at room temperature, and a relative humidity'.

These conditions are the most favourable for 'without water' survival, wereas colder/warmer temperatures, different humidity just decrease the period.

You can also survive more if you prevent water loss.
And, from the same page, the record:
'The crew of a lifeboat reportedly lasted 8 days without water'.