The Hillbilly water filter is a water filter made from trash and what you can find around you. If you can find a plastic bottle or even a can (which unfortunately are everywhere these days), you should be able to find everything else you need from nature in your surrounding area.
Quick DIY water filters such as this are not perfect. They will remove a lot of the bacteria and impurities from the water, but not all. The water will be safer to drink, but drinking it is still not without risk.
The bottom line is – using a filter such as this is all about making the best out of a bad situation. It is not ideal, but it is a vast improvement over nothing.