How fast is a Big Berky, how many gallon per day? An approximation is fine. I don't need precision, just a rough guesstimate.

I would expect it to last a long time filtering water from city plumbing. But how long will it last with rainwater collected from an asphalt roof? Or, water you dip from a ditch, or a neighbors mucky old swimming pool?

Wouldn't the water need to be boiled afterwards, or treated with iodine, UV, chlorine, oxygen, etc.? Most filters cannot get rid of small viruses that cause you the worst health risks.

I am doing a lot of research, trying to find ways to have a source of water encase of a more long term disaster. Water takes up space and is heavy, and we humans use a lot of it. If a disaster lasts much longer than a month or two, having water for it stocked up could pose a problem. Especially since water needs to be rotated pretty regularly.