Abstract: A water filter provides good tasting, potable water without chemical biocides. A water filter utilizing activated carbon to rid the water of undesirable chemicals and the like has dolomite added to the activated carbon. The dolomite acts as a nutrient for harmless bacteria and thereby promotes the growth of the harmless bacteria to the exclusion of harmful bacteria. Dolomite produces a slight alkalinity for improved taste, provides magnesium and calcium as dietary supplements, and encourages the growth of bacteria that produce no undesirable metabolites.