Resource

http://kdvr.com/2018/01/22/water-storage-system-designed-for-hiking-skiing-backpacking-camping-hunting/

https://slate.com/technology/2018/02/filtering-stream-water-or-fresh-water-is-medically-unnecessary.html

https://boingboing.net/2018/03/01/this-water-filter-is-going-in.html

http://www.monktrip.com/complete-working-process-gravity-based-water-purifier/