> Tea quenches your thirst, but coffee does not.

That's not my experience.

>Sure caffiene is a diuretic, but normal coffee as a drink is considered to be one too.

So is water. The diuretic effects of drinking moderate amounts of coffee are no worse than that of water, if you drink it regularly. See, for example http://nordicgroup.us/bikecoff/coffeesexhealth.html for some references. It makes sense if you think about it - some people drink coffee day in and day out, and don't dry up, so it can't be as bad as the urban myth would have you believe.