and electrolytes but I use everything from Gatorade/Powerade/Propel to Liquid IV to plain water. All have their uses. Also, hydrating while you run is helpful, especially on runs in warmer weather that go beyond 45 min or so.
You can pre-hydrate a little but you have to be a little careful so that you aren't needing to pee during the run. And you really can't store much water. I like to be hydrated but stop drinking anything 30 min or so before I run. Then I will hydrate during the run as needed and drink adequate water or other electrolyte drinks in the few hours after the run. I usually drink 20 oz of something with electrolytes right after the run and then just straight water thereafter until I am hydrated again.