[Harmless Teddy Bear]

Coffee acts as a diuretic, which can lead to dehydration—a concern given that most adults already fall short of the recommended eight glasses of water a day.

Coffee is 99% water.

You can not drink enough coffee to dehydrate you.

[cpdiii]

Coffee acts as a diuretic, which can lead to dehydration—a concern given that most adults already fall short of the recommended eight glasses of water a day. Coffee is 99% water. You can not drink enough coffee to dehydrate you.

Incorrect. The coffee represents a portion of your total water intake. If normal renal excretion of urine increases your water balance becomes a deficit until you drink more water. Case in point is alcohol also a powerful diuretic. Drink to much and you wake up with a powerful thirst and a hangover.

Relative to coffee do not even talk to me in the morning until I have had my second cup. I am not nice until then. LOL

[maddog55]

The idea that everyone needs to drink eight glasses of water a day is largely a myth, originating from a misinterpretation of a 1945 recommendation that included water from all sources, not just plain water. Hydration needs vary by individual and can be met through thirst and the consumption of water-rich foods.

[tired&retired]

Coffee has a diuretic effect due to its caffeine content, which may increase urine production. You can piss more water out than you consume in coffee.