How do you get your LO to drink more water?

He is 16 months old and does not like water. Drinks whole milk at every meal. I am worried he is getting dehydrated now that it is getting hotter. How often should kids drink water? I know it sounds like a stupid question. When did your LO start drinking more water and how much do they drink? Any tips on how to get them to drink it more often? I would prefer to not have him drink sugary drinks so I don't want to mix stuff with the water unless I'm desperate.