As others mentioned too much water can be dangerous -- best to balance it with some electrolytes. Also, too much water too quickly (or other liquids) can wash away the mucous coating on your tongue, making you feel worse. It's important to differentiate between a purely dry mouth and other symptoms of dehydration (e.g., dark urine, lightheaded, headache, etc.). If it's true dehydration, treat that since that can cause trouble. If you have dry mouth without other symptoms of dehydration, supplement your liquid intake with an OTC product to treat dry mouth (Biotene makes both a spray and an ointment, which I find helpful when I get a dry mouth). As odd as it sounds, i also find that eating something will help with dry mouth symptoms (my best guess is that because food increase salvation, it helps ease the symptoms).
Hope you get through your flare quickly.
34 - Diagnosed with Crohn's in Nov. '05
Current Meds: Apriso, Canasa, Methotrexate, Pamine Forte, Aciphex, Domperidone, Folic Acid, Restasis, Plaquenil, Doxepin, Xyzal, Zyrtec, Zantac, VSL#3, Calcium, Vitamin D, Centrum, Digestive Enzymes, Thera-tears Omega 3 Supplement, Co-Enzyme Q10
Gluten free since Aug. '03