If you only have a source of disgusting water to drink from.
You can filter it with just a regular plastic bottle.
Simply cut the bottle in half.
Pierce a few holes in the lid.
Fill up your top half with moss…
And some stones.
Throw them in the bottle.
Pour your water through your new, make-shift filter.
Which will leave you with filtered water, free of all the floating chunks.
IMPORTANT: The water is only filtered at this point. You must still purify it.
So take your other half of the bottle. And put it in the fire to boil and purify.
Again, be aware of the fact that boiling water in plastic will release carcinogens (cancer-causing chemicals) into the water