Water filtration system

A water-filtration system includes four distinct porous media through which water is sequentially routed in a compact, self-contained four-stage filtration process. The porous media improves water quality by removing unwanted contaminants from the water and adding minerals and compounds to the water to improve water taste. A housing contains the the porous media. The housing includes connection points for incoming and outgoing water. The water-filtration system may be inserted into a water line upstream of a desired source of high-quality water, or may be integrated directly into an appliance or device that requires high-quality water.