Since I started running, I've gotten into the habit of always having a water bottle with me. It doesn't matter if I run 3 miles or 13; I have it handy. My philosophy is that if I don't have to be thirsty, then why should I? I never carry it in a race, though; no problems switching from a constant source to an aid station-based source.
For most of my short runs, I only need a small bottle. I've tried three different types: the Fuel Belt Sprint, the Amphipod Thermal Lite, and the Ultimate Direction Fastdraw. These are in the 10-12 oz range.
|The Ultimate Direction Fastdraw; great, reliable bottle.|
My favorite is the Ultimate Direction. It is more secure than the Fuel Belt; I've never had a bottle slip out. Also, it is easier to open while running. I've had the "nipple" pop off of the Fuel Belt before. This has never happened with the UD. Once you get a couple of carriers ($14.95 for bottle and carrier), you'll only need to buy bottles for replacements ($5 each) or just replacement tops as they become scratched or worn (takes a long time). The Amphipod is a decent choice, but the UD has a better pocket for money, ID, small packets of nutrition (like Sports Beans), or even tiny MP3 players like the Shuffle or Clip Zip if you want to stash that kind of stuff. I put the UD bottle/cap in the dishwasher all the time; never a problem. You can machine wash the UD carrier (I don't know if it is recommended, but I have several times). Highly recommended!
I hope your progress is going well!