Epiphora (Tearing) Remedies

We have a 4 yr.old male maltese and he has very bad tearing/staining from his eyes. I have given him filtered water and/or distilled water since he was a puppy but it has not seemed to help. I never give him tap water. This is in reply to the posts about the filtered water. Does anyone have a similar experience? This has been a problem for 4 years. Thanks!