Had me worried there for a minute. I thought it might be a sexual thing.

That said, if you drink from springs or streams, you need to use some common sense. Sometimes common sense isn't enough.
LOL, though I'd bet the mountain men going a whole winter without seeing another human being, let alone a woman, got a form of the beaver fever!
But what I was talking abut was, it was pretty early on that some people got the idea that not all water was good, and boiled it. In a history of the building of the transcontinental railroad, there was an interesting passage about how the Chinese workers on the Western Pacific would not drink the water. They would make large kettles of tea, and put the tea in the water bags and drinking water barrels. The white railroad workers drank water from the barrels that came from whatever local streams or rivers, and they had a lot of intestinal diseases, while the Chinese had very little disease.
Some west point officers had a similar idea, and one George Custer had his canteen filled each boring with coffee, and recommended this to all his company commanders. Maybe if he'd drank tea instead, he would not have rushed headlong into a certain valley!
I can only wonder how may of those old cowpokes bothered to make a fire to boil water for a pot of coffee because on some gut level they didn't trust the local water?
To not derail the thread, I guess it's possible to go camping today with modern water filters and tiny alcohol stoves, but I just can't bring myself to leave the fixed blade behind. I'm a 'what if" kind of guy, and worry about fuel canister leaking, stove breaking if fell on in a fall while wearing the pack, Or just someone slipping a breaking a leg. The last has happened to me once, and I was caught short and had to make do with a pocket knife. Never again. To me, a fixed blade in the pack is like a spare tire. You hope you don't need it, but if you do, you'll need it very badly. But carry what yopu like, it's a free country. Most people carry a Bic lighter, but I still like the old barn burner large wooden matches in a water proof container to back up the lighter. There's a fire steel in the little emergency pouch in the pack. I consider the ability to make a fire quick a mandatory skill to have. If it's been wet, you'll need something more than a pocket knife.