• Exceeds purification standard (log 4)
• MS2 Coliphage
• En Coliphage

• Bacillus atrophaeus (anthrax substitute)
• Raoultella terrigena (substitute for pathogenic bacteria)
• Salmonella Enterica

• Bromodichloromethane
• Bromoform
• Chloroform
• Dibromochloromethane

• Chloramine
• Chloride
• Residual chlorine (total residual chlorine)
• Chlorine

• Aluminum (> 99%)
• Antimony (>99.9%)
• Barium (> 80%)
• Beryllium (>99.9%)
• Bismuth (>99.9%)
• Cadmium (>99.7%)
• Cobalt (>95%)
• Chromium (>99.9%)
• Chromium 6 (>99.85%)
• Copper (>99.9%)
• Iron (>99.9%)
• Lead (>99.9%)
• Mercury (>99.9%)
• Molybdenum (>90%)
• Nickel (>99.9%)
• Vanadium (>87.5%)
• Zinc (>99.9%)

• Acetaminophen
• Caffeine
• Carbamazepine
• Ciprofloxacin HCl
• Erythromycin USP
• Sulfamethoxazole
• Trimethoprim; Bisphenol A
• Diclofenac sodium
• 4-para-nonylphenol
• 4-tert-octylphenol
• Primidone
• Progesterone
• Gemfibrozil
• ibuprofen
• Naproxen Sodium
• Triclosan
• Chlorothalonil

• Arsenic (>99.9%)
• Escherichia coli (E.coli) (>99.999%)
• Fluorene (>99.9%)
• Manganese (>99.9%)
• MBAS (>96.67%)
• PCBs (>99.9%)
• Petroleum products (gasoline, diesel, crude oil, kerosene, mineral spirits, refined petroleum – all >99.9%)
• Selenium (>99.9%)
• Thallium (>99.5%)
• Rust
• Silt
• Sediment
• Turbidity
• Tastes and smells

The first line of defense against contaminants is the materials Black Berkey filters are made of. Each cylindrical filter is composed of a formulation of more than six different types of materials, all constructed in a very compact matrix containing millions of microscopic pores. The microscopic topography of the surface of the filter elements contains millions of tiny holes that allow water to pass through. These holes are so tiny that pollutants cannot physically pass through them. Thus trapping the smallest pathogenic bacteria, cysts, parasites, sediments and sedimentary minerals.

Adsorption has the effect of creating an ionic barrier similar to surface tension. The barrier that stretches between the micropores blocks water contaminants, such as submicron viruses, which are smaller than the pore size itself. Berkey filters take advantage of the electrostatic charge of viruses and pull them against the walls of tunnels in the "tortuous path" of the filter. Like static cling, it holds tiny viruses to the filter surfaces and won't let go. The Berkey has the prestigious classification as a water purifier, not just a water filter, due to its ability to remove viruses. Other water filters cannot without the use of harmful chemicals like iodine or chlorine.

The technology used by the Berkey for this stage of the filtering process is ion exchange. This process is similar to leaving an open box of baking soda in the refrigerator to absorb bad smells. Heavy metal ions (molecules of chromium, lead or copper) are extracted from water by an ion exchange process where they are attracted and transformed by bonding electrically to matter. Ions are unbalanced molecules, the number of electrons is not equal to the number of protons. Molecules want to restore balance and are therefore attracted to other molecules that balance their charge. Black Berkey filters are charged with ions that attract contaminating molecules. These molecules are absorbed and permanently bound to the filter, never entering the drinking water in the Berkey's lower tank.

Finally, due to the gravity flow nature of a Berkey, water molecules take several minutes to pass through the filter elements, whereas molecules from other filtration systems pass in fractions of a second. The longer contact time between water molecules and filter media results in much higher removal rates of harmful contaminants from water than those achieved by conventional pressurized water filtration methods .