Why are water filters so important to America and what was life Before it was invented and what did people do when the water was not filtered?

Why are water filters so important to America and what was life Before it was invented and what did people do when the water was not filtered?
If it wasn't for filters the water would be filled with unwanted garbage. Before filters they had wells which was usually had pretty clean water, if not that then lakes or streams that the water would had of been boiled unless you want parasites that is.