PS. - All that said I usually carry a treatment that is good against viruses for those cases where I suspect that the load of infectious diseases in the water are likely high.

Traveling in the remote swamps or the SE well away from populations and in areas seldom traveled by hikers or hunters I feel pretty confident in just filtering the water.

In a case where the water is likely contaminated by sewage, like the flooding seen in NOLA, I would use a treatment that pounds on viruses.

Of course in that the water also has oil, pesticides, other toxic chemicals along with raw sewage and every other possible contaminate so I would use every method I could reasonably manage.