This is the best deal we have ever found on Big Berkey “Black” Water Filters at about $51 each. Please send us a link if you can find these cheaper anywhere else. These filters are for a Big Berkey or a DIY Berkey too. Together these four (4) filters provide a total treatment capacity of 12,000 gallons. Berkey filters provide almost 100% reduction of pathogens including Giardia, E. Coli and many other pathogens, heavy metals and harmful compounds – read more here. We highly recommend Berkey filters as the cornerstone of your water purification system.