A lot of human survival is based on heuristics, if you can tell there's a corpse in something, you probably shouldn't drink or eat it... As a general rule of thumb
For large body of water since you're unaware of the corpse two kilometers away on the bottom, it's probably not an issue for you.
However, primal human heuristics are not calibrated correctly from modern media. There was the reservoir where somebody was caught on camera peeing into it, hundreds of millions of liters of water, and they decided to drain the entire thing to prevent the public concern. That's just a heuristic run amok
A lot of human survival is based on heuristics, if you can tell there's a corpse in something, you probably shouldn't drink or eat it... As a general rule of thumb
And this is why it's dangerous to drink ocean-water.
Also why you should drink lots of that delicious peepee pool-water
ETA: If you're having dinner with someone who dies in the middle of eating their food, you can safely finish their food, drink, and poisoned soup as long as they didn't die face-down in it.
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That's what's literally happening in your kidneys. Your primary urine is low concentrated, and gets converted into high concentrated secondary urine through several fun biophysicochemical reactions. Boring piss gets to be exciting piss. Wohoo?
Also what is the intermixing of water two kilometers away, especially affected by currents (which I presume, without checking ofc bc this is the internet 😁, are more horizontal than vertical - thus would intermixing occur more readily on the horizontal but the fact that it's vertical distance mean... what really)? So yeah, it makes sense then that due to the unknown factors, the default would take over.