Plastic bottles can be reused after you’ve finished using them the first time. Often the uses are a lot different to it’s original purpose. This one’s quite helpful if you ever find yourself with a microbially infected water supply. Fill the plastic bottle with the water, place the bottle in the sunlight, ontop of a reflective surface. The microbes are broken down by the UV light, let in by the plastic, and the heat of the water, caused by the surface and the sunlight. Depending on the quality of the water, it can be ready to drink within 50 minutes.