A great use for unwanted and used plastic bottles...ICE PACKS!!!
Fill the empty and rinsed out plastic bottle about 3/4 full with water.
Secure the cap and freeze.
These handy items can be used in your lunchbox, cooler, or to ice an injury from your latest instructable experiment. Not only are we recycling plastic bottles we never have to change the water.
Step 4: Warnings
NOTE: Do not drink the water because it has been said that plastic bottles release a toxin when frozen. Potentially fatal or cancerous if you drink out of a frozen plastic bottle.