Daily salivary secretion is

The amount of saliva that is produced in a healthy person per day; estimates range from 0.75 to 1.5 litres per day while it is generally accepted that during sleep the amount drops to nearly zero. In humans, the submandibular gland contributes around 70-75% of secretion, while the parotid gland secretes about 20-25% and small amounts are secreted from the other salivary glands. Ref: guyton and hall textbook of medical physiology 12 edition page number: 400,401,402