How dehydrating is caffeine?

Question

I know that caffeine is a diuretic and causes the kidneys to remove more water from my bloodstream than they would normally.

The question is how much? If a 300ml cup off coffee has one hundred milligrammes of caffeine (on average say), what would the water deficit in my body be, and how much water would I need to drink to make up the difference?

Answer 1

its drys you out

Answer 2

I asked the same question a few years ago. Basically the diuretic effect is minimal.  Maybe an additonal 8oz. glass of water. per cup of coffee.  I switched to decaf. (swiss water decaf.)  I don't drink cola or drinks with caffeine.  I might drink one cup of regular coffee a year, at best.  

Answer 3

>>its drys you out<<

Not only that, but it dehydrates you as well! LOL!

Caffeine is a diuretic, so it's best to minimise the intake of stuff like coffee that contains lots of it.