After eating solids, what kind of water do you give to your babies? Distilled, Boiled or MIneral?

I gave my son a little boiled water when he started eating at 6 months plus. He had constipation for months eversince he started eating even though he was fully breastfed. It was so hard for me to get him to drink just abit of water. But fortunately his stools got so much better after I trained him to drink mineral water eversince he was about 8-9 months old. He is 18 months old now and drinks alot of mineral water everyday. But different things works for different babies :)