Ensure pure water free from bacteria, viruses & heavy metals with DuraFlo™ replacement water filter. This pack of 4 filters can purify up to 4x700 gallons. Use the DuraFlo™ Water Filter Replacement in your AquaBrick® System to effectively remove virus, bacteria, giardia, cryptosporidium, and other water-borne toxins and chemicals from ANY nonsalt water source. HIGHLY EFFECTIVE REPLACEMENT FILTER FOR MOST COUNTER TOP, GRAVITY FED WATER FILTER SYSTEMS, INCLUDING BERKEY®.  INCLUDES FILTER ONLY