When my kids were infants, I gave them sips of water from my glass (with help of course!) When solids were introduced, they had a cup of water on the high chair tray. When we're out and about, I always have a water bottle with me and share it with the baby as needed (now I sometimes share with my big kids and sometimes pack extras for them.)
Juice was always an occasional treat- the only one who got it as an infant was DS, and then it was almost always watered down, and never more than 4oz per day (often only 1oz or 2oz per day). If he got a 4oz bottle of undiluted juice, that was IT for the day- only breastmilk or water was offered later!
I never let my kids get into the "juice habit" and every single one of them enjoys plain water. It's much harder to change habits once they've been developed, but it still can be done. How old is your son and just how much juice is he drinking per day? I'd have different advice if he's 15mo or if he's 3yo.