>Drinks directly from a stream without so much as filtering it or boiling it
You have the healthy immune system of someone living a 1st world country that has never known having to drink questionable quality water. You have never likely encountered water-borne pathogens and bacteria enough to develop a resistance to it. So, pretty please, whether you find yourself isekai'd away or stuck in the mountains - don't fucking drink the water straight. Even if all you can do is strain it through a shirt and leave it out in direct sunlight and hope UV kills something, that's MULTITUDES better than drinking water straight from a stream. Guess what is also in that stream? Fish. Animals. Things that shit in the water or die in the water. Things you don't have a built-up immune system from living in squalor and drinking from wells that have been contaminated with run-off or from stagnate sources of water or nasty-ass ponds. So... don't do this. Unless you are LITERALLY dying of thirst and have gone 3+ days without water and this is your only source... Just don't. You getting diarrhea will only hasten your dehydration. You vomiting will only make your dehydration worse. So unless you're likely going to die anyways, at least filter or boil the water.
>"DEMS CRUSTACEANS IN DEM DER STREAMS, IT'S POTABLE! POTABLE, I SAY!"
...No. First of all, the whole "there's no pathogens because they are there" is... utterly laughable. Secondly, there's plenty of saltwater shrimp and the like. And he has no idea how different, if at all, life on this entirely different planet is from our own. Hell, I wouldn't assume this on Earth, let alone another planet.
Even the Bear Grylls "I'm lost in Walmart, better drink my own piss and go to the hotel to 'survive' the night" model is better than what this guy is doing.