@irenea8 and @nana43 When I asked Life Straw if their most filtered water was safe for rinsing nasals, in other words, is it the same as boiled water, they replied as quoted below. They did not really answer the question, other than to say, it's not the same as boiled water! According to their answer, it sounds a little better than boiled water....? Maybe those who have researched this more will weigh in.

"LifeStraws are not quite the same thing as boiled water.

Boiling water will kill all the pathogens in your water: viruses, bacteria, parasites, cysts, etc. Boiling water does not always eliminate chemicals and heavy metals in the water. It does not address microplastics or debris in the water.

We have a couple of kinds of filters and purifiers that do different things:
Filters: these remove bacteria, parasites, cysts, microplastics and cloudiness / turbidity. They do not remove viruses and chemicals/heavy metals.
Filters with activated carbon: in addition to filtration capabilities, they also help reduce and remove chemicals and heavy metals.
Purifiers: these remove viruses, bacteria, parasites, cysts, microplastics and cloudiness / turbidity."