There are two reasons that cause watery eye. On one hand, blocked tear ducts is the most common cause of watering eyes among adults and older children. On the other hand, over production of tears can cause eye watery. It is usually caused by some chemicals, allergic conjunctivitis, allergic conjunctivitis and ectropion. For children, the watery eyes are usually caused by the blocked tear ducts. Because some babies are born with excessive eye watering and their tear ducts do not develop fully. To treat watery eyes, the first step you should do is to have a full eye examination to identify the cause of watery eyes. If the watery is cause by blocked tear dusts, you can have tear dusts opened instead of surgery.