Water only relieves dry mouth for about 12-16 minutes, but still an option. Milk replicates saliva. Sugar increases salivation, but maybe not good for the teeth. Smelling lemons, citric candy, chewing gum, sucking on pits from pit fruit, drinking lemon water helps produce saliva. Even sering smelling, thonking about food helps produce saliva. The salivary glands basically shut down at night, causing dry mouth, and those sleeping with the mouth open, more so. There are some mouth straps for snoring that help keep the mouth closed, and know of some using tape to keep the mouth closed. I used biotene dry mouth gel at night, but don't know how the product is these days, Vaseline or chap sticks on lips to prevent dryness, in addition too using dry mouthwash, toothpaste.

Daily requirement for water varies for each individual, based on height, weight, altitude, illness, medications, pregnancy, humidity, activity, and I always went by half your body weight in liquid ounces just to begin with, which formula basically comes to it. They say no more than 20% should come from eating food, and the rest liquids. There are plenty of daily water calculators on-line, ipad has water apps for free. For me, it was 128 ounces, and was surprised myself. I forget my weight then, maybe 180lbs, and half that is 90 ounces, not including the need for more. I don't think I ever drank that much, but if I was ever hospitalized for another reason, I was always treated for dehydration too.