No amount of water will do, if dry mouth is not caused by dehydration. Dry mouth can show up during hormonal changes such as menopause and perimenopause and although low estrogen is blamed for that, it is only partially true.
Saliva production is strongly linked to metabolic health and dry mouth can be a sign of its decline.
One way to check whether metabolic health is contributing to dry mouth is to check saliva pH. Do it especially if you are overweight, and definitely, when you are a diabetic. For instructions and details, see the video.