I was curious if anyone had used a MSR guardian purifier. It's a newer product. It filters viruses and bacteria without using chemicals and has a claimed 10,000 liter life. It's expensive at $350 but not bad if it lives up to a 10,000 liter life on the filter element. It is supposed to have the long life because it automatically backflushes during use.

It would be an ideal prepping item.