How did mountain men, cowboys, or settlers going west purify water before drinking? Survival shows today have people boiling it or some sort of sterilization technique either natural or manmade before ever touching a drop. Never do they just stick their face in a creek or water hole for a drink for fear of beaver fever and getting diarrhea.
If you have a low enough population density, don’t live in towns, don’t farm, raise cattle and if you do, don’t drink the water downstream the herd. You also didn’t dig your well downhill from the outhouse.
They didn’t purify it because they didn’t understand that water could spread disease. That’s why cholera devastated and sometimes wiped out entire communities, both Indian and white. They would have sought good-smelling or flowing water if possible, though and they might have boiled water to remove a smell. People have known this since the ancient Greeks.
Following a cholera epidemic in England in 1854 it was discovered the disease spread through water. They also found the contaminated water tasted and smelled normal proving that alone didn’t guarantee safe drinking water.
A British scientist, Dr. John Snow, was convinced that water, contaminated by sewage was the cause of cholera but he couldn’t convince his colleagues until a mother washed her baby’s diaper in a town well in 1854, that touched off an epidemic that killed 616 people. He applied chlorine to purify the water and this paved the way for water purification.