Following are the causes of watering of eye;
1) Dacryocystitis; inflammation of the lacrimal gland. This can be acute or chronic in onset.
2) Conjunctivitis; pink eye
3) Nasolacrimal Duct, Obstruction
4) Glaucoma; increased eye ball pressure
5) Blepharitis refers to an inflammatory disease of the eyelid
Please feel free for your follow up questions.