Nowadays everything comes in packaging. We (Human Population) throw so much away even though we can just reuse them. I researched some way we can reuse plastic bottles and here are my findings.
Water for the Freezer
If you have loads of space in your freezer, Consider filling up bottles with water and place them into the freezer. This will result in a) save energy b) if electricity fails the freezer will stay cold longer. When filling up bottles, make sure you do not fill them all the way. Leave about 1/5 empty because the ice in the bottle will expand.
Use as Funnel and Flower Pot
You can cut the bottle in half. The top bit you can use as funnel in your garden when working with chemicals or any other liquid. The bottom you can use as flowerpots.
Shakers
You can fill them with little things like pasta, rice, stones, buttons and give them to children to play with. But be careful that you don't give them too many shakers; your ears might suffer.
Collect Bits and Bobs
If you are having a lot of little bits like buttons, screws or nails you can store them in small bottles. You can label them or paint them to look nicer.
Birdfeeder
Fasten a piece of string to the lid and cut out holes at the bottom. Make sure the holes are big enough for birds to get in. place a little bird food at the bottom of the bottle and enjoy watching birds feeding. You can also paint the bottles to make them look better.
Water Bottle Rockets
You can build rockets that are powered by water with them. There are many guides on the internet that explain how to build them and how to use them. great fun for children.
There are reports that you shouldn't reuse plastic bottles as drinking bottles. The reason they state is that the plastics will release cancer causing chemicals. I am not sure what to think about it but to make sure I will not tell you to reuse them as drinking bottles.