Well I'm a First Need fan.  Have used one for years now in water I know for a fact had Ghiardia, however its really not a bucket volume type filter.  The gravity feed bag is pretty handy and thought about adapting that to say a five gallon bucket as needed, but then when you think about it, when we need these things how often will we have company anyway?

Instead, I've gone with a two phase approach dependent on starting water quality.  A simple ceramic 0.2 micron filter for high volume filtering for cooking (cooking kills the germs) and the First Need for drinking with using a simple charcoal filter like you buy anywhere, Pur etc, for chemical removal.  Its real easy to adapt those commerical charcoal filters that are threaded to about anything you want. I simply use those on my facets now, keeping spare filters, and have the adapters in my tool box for what if.

Of course, my fall back is always the First Need for drinking water.  Filtering virus without a chemical treatment, IMHO is a big deal especially if hot stagnant water is involved.  Cold water, not a big deal.

Anyway, the point of my post is commercial residential water treatment is a big industry now and prices remarkably low for the same technologies we pay big bucks for in a hiking or survival setting.  It behooves us to take advantage of the technology and not pay so much attention to packaging.  Its not that hard to have some tubing and adapters around.  

Tj