Most people should drink at least 7 to 10 average sized glasses of water each day. Many people do not drink enough water and the consequences of this can be severe. People often think that drinking cups of tea, coffee or even alcohol makes up for not drinking water. This is incorrect. Instead of quenching your thirst these drinks can actually make you feel more thirsty

http://archives.cnn.com/2002/HEALTH/diet.fitness/05/24/cohen.water.otsc/index.html