This is an instructable on how to make a water bottle carrier to hook on your belt.

Step 1: What You Need

Some cord (Nylon or Polyester is best)
1 in Nylon Strap (the kind used on backpacks)
Drawstring Stoppers (like what you might have at the end of a hoodie string)
A Carabiner (AKA Spring Link)
A lighter will help you melt the ends of your cuts
and Scissors and a ruler (not pictured)

I actually salvaged these parts to make this, cord I had laying around, the strap was cut off an old messenger bag and the drawstring stoppers were from an old coat. Never throw these plastic pieces out. Even if you buy all of them it would still only be $5 or $6.

Step 2: Bottle Carrier Loop

This is the loop that will actually carry the bottle.
First, cut a length of cord. Mine is about 15 inches because I have a large mouth water bottle. If you are only carrying a store bought bottle or a sport drink you can use about 10 inches.
Second, Tie the ends to make a loop. (go ahead, use a square knot)
Finally, push the loop through the drawstring stopper. You may need to use a toothpick or something like that to push the cord through.

Step 3: Make the Strap

Now, to make the strap to connect the bottle loop to the carabiner.
First, cut the nylon strap. I first cut a little over 9 inches, but this turned out to be too long. I only needed about 6 inches. (no jokes please)
Second, place the knot from the loop on the strap and fold about 1 inch over. This will hide the knot. Then sew the flap down. I used red thread to highlight the pattern I used. It's hard to tell by the picture, but I sewed over and through the cord, through the strap on both sides of the knot. This will keep the knot from sliding out.
Third, fold over the other end of the strap, about an inch, and sew down.
Fourth, fold the same end over again, bringing it all the way down to the flap at the other end of the strap. Sew the flap down, leaving a loop at the end of the strap for the carabiner to go through.
Finally, insert the carabiner.

Step 4: Now Use and Enjoy

Place the loop over the lip of the bottle and cinch the drawstring stopper.
Clip to a belt loop and enjoy.

Step 5: A Little Bit More

I've also made a version to hang over your neck or shoulder. The steps are the same, but you use a much longer strap, and make the loop that would be for the carabiner large enough to fit over your neck or shoulder. To measure for length, after you sew in the bottle loop in step 3, place the strap how you intend to wear it, cut it, and sew.