It's not just about keeping your mouth moist and your kidneys kidney-ing: Taking in fluids lets your body thin out mucus and ease its journey through your sinuses, lessening the chances of booger-based logjams, too [source: Doheny].
Your body is 60 percent water by volume, and just about every activity of life it carries out requires water: moving nutrients; flushing toxins; dampening exposed tissues in the ear, nose and throat; controlling body temperatures, heart rate and blood pressure; and so on [sources: Mayo Clinic, Soong]. Keeping the works running smoothly means replacing the water that you continually exhale, sweat and void. The Institute of Medicine endorses a daily beverage intake of 13 cups (3 liters) for men and 9 cups (2.2 liters) for women [source: Mayo Clinic]. When in doubt, drink enough water to keep your pee colorless [source: Doheny].
Milk and juices hold plenty of water, as do many fruits and vegetables, and coffee and tea contain more than enough water to offset the dehydrating effects of caffeine — although it's still a good idea to add a little extra if you find yourself peeing more after that second cup.
Sinus Congestion Tips
Here is some information to help you with sinus congestion.