What's happened? You used to "debate" logically but just lately you've resorted to....... less than "nice" comments.

There was no need to say "that is a ridiculous statement". You've not thought it through.

In the video, there is absolutely no sign of them having made any attempt to keep the water clean(er).

Where you have a spring, you scrape back the ground to the point where the water emerges and protect that area from animals. As the water flows, it only needs to flow a little way, (a few yards will do) to a place where you clear the stones, then use them to make a little dam to encourage the animals to drink there.

As to getting a water supply if society broke down, that might be the least of my worries............

There's plenty of water round here, it'd be a matter of fetching it..........