I’ve recently decided to take a more active role in my own emergency preparedness.

I’ve been looking at water filtration systems from the perspective of trying to figure out how good they are at removing contaminants. As no filter can kill viruses, naturally a secondary chemical disinfection would insure against the little nasties. My attempts to find information however on filter’s capabilities to deal with chemicals has left me unsatisfied. The descriptors used with active carbon seem to always be removal of taste and smell. Other methods also clearly seem to indicate stuff still gets through.

So if you had to assume the water was contaminated by more then just microscopic lifeforms, just how well do these things perform? If we assume the absolute worst case scenario and the water was laced with CBR contaminants would your normally available man portable filtration systems and chemical disinfection serve you against more then just the B component?