I've been using a 25-year old fanny pack to carry my water and Gatorade. It is a small pack and is just big enough for a 20-ounce bottle of water and one full of Gatorade. I noticed a few days ago that the seams in the pack (it is made of canvas) are tearing out, because I also stuff in my cell phone and car key. I decided to splurge and get a Fuel Belt that carries six 8-ounce bottles. That is 8 ounces more that I was carrying on hot days. The belt also has a nice pouch for my cell phone and key. The bottles are distributed uniformly around the belt and thus help to keep me balanced.
The fuel belt worked fine on my run this morning. I used three bottles, two of water and one of Gatorade. I've been drinking half water and half Gatorade, and I decided last week to go to a 2:1 ratio. It took just a few minutes to get used to removing and returning the bottles to the elastic "pockets" on the belt.