Indeed, neither coffee nor tea nor other caffeinated beveages appear to promote dehydration in anything remotely resembling reasonable intake:
- Kinderkrankenschwester. 2010 Jun;29(6):256.
[Coffee does not cause dehydration!].
[Article in German]
Flemmer A.
- Br J Nutr. 2011 Aug;106(4):588-95.Epub 2011 Mar 30.
Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trial.
Ruxton CH, Hart VA.
Int J Sport Nutr Exerc Metab. 2005 Jun;15(3):252-65.
Fluid, electrolyte, and renal indices of hydration during 11 days of controlled caffeine consumption.
Armstrong LE, Pumerantz AC, Roti MW, Judelson DA, Watson G, Dias JC, Sokmen B, Casa DJ, Maresh CM, Lieberman H, Kellogg M.
J Hum Nutr Diet. 2003 Dec;16(6):411-20.
Caffeine ingestion and fluid balance: a review.
Maughan RJ, Griffin J.
Cheers,
DocVikingo