Thanks for posting your query.
In infants as well as in old age individuals,salivation will be usually increased due to lack of control of cheek muscles over saliva secretion.
Usually at the age of 6-7 years ,child will attain the capacity to control drooling
This is usual in your baby's case.
Also there will be gag reflux,due to which child wont be able to open moth for more than 15 seconds,which in turn can lead to drooling of saliva,water etc.
If salivation is too high,anti-sialogogues has to be administered.
Hope this helps.