I used to only bring hydration with me on runs over 4 miles, but lately I've needed a full 20oz bottle of electrolytes on all of my runs. A few months ago, we purchased this Nathan Hydration Belt. This thing has been well worth every penny this summer! If you do any walking or running out in the heat, this little baby will be your BFF. There are fancier models, but this one does the job.
There was a slight conundrum with the spout leaking. I normally fill it with water, or Sustain the night before and refrigerate for use in the morning. Last night, my brilliant husband solved the problem. He went out for 5 miles around 8pm and didn't have time to chill his water. He came back and reported that it didn't leak a bit...seems chilling the bottle stiffened up the spout making it unable to fully close. This morning, I used chilled water from the fridge to pour into the room temp bottle - worked great, and no leaks!
Happy sweating, heh-heh.