A modular water treatment system includes a plurality of water treatment components selected from a group of a particulate filter component, a taste and odor filter component, a lead and mercury filter component, a water softener component, and a water disinfection component. The water treatment system also includes a plurality of interfaces for coupling to the selected water treatment components, and plumbing lines providing flow communication between the selected components, the plumbing lines comprising a system water inlet and a system water outlet.