Coffee dehydrates even more. I was 10 cups per day before I began vaping and now drink 2 cups + 2 cups decaf.
From the Mayo Clinic:
from Katherine Zeratsky, R.D., L.D.
Researchers used to believe that caffeinated drinks had a diuretic effect. This means that you would urinate more after drinking them, which could increase your risk of becoming dehydrated. Recent research shows that this is not true and that caffeine has a diuretic effect only if you consume large amounts of it — more than 500 to 600 milligrams (the equivalent of 5 to 7 cups of coffee) a day.
From the Mayo Clinic:
from Katherine Zeratsky, R.D., L.D.
Researchers used to believe that caffeinated drinks had a diuretic effect. This means that you would urinate more after drinking them, which could increase your risk of becoming dehydrated. Recent research shows that this is not true and that caffeine has a diuretic effect only if you consume large amounts of it — more than 500 to 600 milligrams (the equivalent of 5 to 7 cups of coffee) a day.
Does coffee count? I'm not much of a water drinker but I drink 6 to 10 cups of coffee a day.