I carry a Lifestraw as a backup most times, but after several years of that I've still not used it yet. Everything I've read about them says they work. I have no reason to doubt they do. But, they're made for drinking out of, not for filling a container, so they're limited by that. That company does make a gravity filter version, but it's pretty expensive by comparison so I'd opt a Sawyer Mini Squeeze filter before getting one of those.

Personally, I won't use chorine. I use a lightweight and inexpensive activated charcoal filter made by Britta (the one made for their "Squeeze" bottles), and if I'm not getting my water from a clear running spring I'll boil it after filtering it.

The reason I don't use chorine is I suspect it probably kills good gut bacteria which makes you more susceptible to things giardia, cryptosporidium, E. coli, etc.

I don't always boil my water because drinking from local sources helps build your immunity to things like E. coli, giardia, and cryptosporidium that may be living in that area's water sources. But, I've not taken any antibiotics in years, and that's an important factor in how susceptible you are to getting sick from these bugs.

If you have taken antibiotics recently it's best to make sure your water is throughly sanitized and best not to use chlorine at all. Both of those kill off your good gut bugs and increase your risk of misery by a lot.

All that said, I'm probably the only here who does this, so keep that in mind