If modern people went back to the past, they wouldn't be able to survive because of the filth, right?

I've been reading a martial arts web novel lately.
It's about a protagonist who is reincarnated as the young master of the Sichuan Tang Clan in the 1500s and rebuilds the clan using modern knowledge and experience.
He builds things like water and sewage systems, railways, steel mills, gunpowder weapons, and so on.
In the beginning, some details came up that I had never really thought about before:
The entire street was covered in excrement.
People would relieve themselves in their rooms and then immediately dispose of it outside their houses lol.
Commoners would just scoop water directly from wells, and in places with poor water quality,
they would just scoop up muddy water and wait for the sediment to settle before drinking it.
Living alongside all sorts of insects was just a daily occurrence.
It's terrifying just imagining it.