DIY Emergency Water filter
If you are in an emergency situation where you don't have access to clean drinking water, it's fairly easy to build a DIY filter to clean up 'less than pristine' water.
This filter will clean out the larger particles, making it look crystal clear. However the water will still contain bacteria, viruses and parasites. Make sure you take the extra step of boiling your water to kill these bad guys.
has list of other chemicals to kill bacteria:
https://www.epa.gov/ground-water-and-drinking-water/emergency-disinfection-drinking-water
cdc recommends 1 minute boil
https://www.cdc.gov/healthywater/emergency/making-water-safe.html
https://www.wikihow.com/Make-Activated-Charcoal
can use calcium chloride(Ice melt pure enough?), lemon juice or bleach
Diy activated charcoal with lemon:
https://www.youtube.com/watch?v=1kySEZxA3Gc
https://www.youtube.com/watch?v=4N5hdOcsKrg&t=57s
Good video KOR does it all.
https://www.youtube.com/watch?v=eOxZrCAPhok
use cilantro to remove heavy metals from water
https://www.institutefornaturalhealing.com/2016/07/fast-and-natural-way-to-purify-tap-water/
apple peals and tomato skins remove heavy metals
https://dailyhealthpost.com/fruit-peels-help-remove-heavy-metals-and-purify-water/2/
things to watch out for in drinking water:
Metals (iron, lead, mercury)
Harmful chemicals (pesticides, herbicides, etc.)
Pharmaceuticals