Following are the common cause of metallic taste in mouth;
1) Medications like Antibiotics, Prenatal Vitamins and Antidepressants
2) Oral Infections like Gingivitis or Periodontitis
3) Poor Oral Hygiene
Please feel free for your follow up questions.
A salivary gland inflammation needs to be considered for watering as irritable gland do secrete excess saliva. Your primary care physician can examine or palpate all three major salivary gland; namely parotid, submandibular and submental. Herbs too can be responsible for the metallic taste and irritation of the salivary gland resulting in increased production of the saliva. But many times it subsides spontaneously and no cause is found. Read about the excessive saliva in this authentic resource;
If above causes which I mentioned can be ruled out, consideration of the gastroesophageal reflux disease (GERD) should be done. Anxiety and emotional disorders also are considered cause of excess water in mouth. Read about the GERD symptoms;
You are welcome.
A positive feedback would be appreciated.
Best wishes and kindest regards.