If he is breastfed only he does not need additional water, but he is on other feeds by now. From 6 to 12 months, babies do not need much water but introducing some in a bottle or sippy cup can help them get used to the taste (or lack thereof) and consistency of the liquid. Limiting water to about 2 to 4 ounces per day is the typical recommendation as babies make the transition from an all-liquid diet
to one involving solids, although some babies may benefit from closer to 6 to 8 ounces per day (such as in the case of constipation
or extremely hot and humid weather).
For regular advice on child rearing ask me privately.