Question of the Day: Hydration

Yesterday, I went out for a longer walk – my Thursday walk-and-talk with my brother, which ends up being longer (and farther) than every other day of the week (especially now, since my Summer Walking Buddy makes me turn around sooner). That long walk was HOT – and while I had my water bottle with me, I knew that I needed more than just my handheld flask to make up for it.
During these warm summer months, how do you hydrate? What do you carry with you on your walks? And do you hydrate extra after you get home?