The body has a number of different salivary glands. There are the parotid glands within your cheeks (one on each side), which are the largest salivary glands you have. Next largest are the paired submandibular glands which are located underneath the body and angle of the mandible (jaw bone). There are paired sublingual (underneath the tongue) salivary glands, and then there are hundreds of minor salivary glands all throughout your month and pharynx (soft palate, etc). Sialorrhea, or overproduction of saliva, can have many different etiologies. First of all, there is a continuum of "normal" and the fact that one person produces more than another doesn't necessarily mean that there is a pathology present. In general sources of sialorrhea can be broken down into two main categories: actual overproduction, and impaired clearance of the saliva that is being made. For instance, if there is a swallowing problem, then the individual may experience excess saliva despite the fact that the production hasn't changed. There are numerous factors that can cause overproduction of saliva including; serotonin syndrome, pregnancy, oral infection, pancreatitis, or reflux disease (this list is by no means all-inclusive). I would recommend making an appointment with an ENT (Ears Nose Throat) physician to get evaluated. Best of luck.