Abstract: An electrolytic treatment apparatus includes a substantially hollow tubular outer vessel housing closed at its bottom end and provided with a liquid inlet and liquid outlet adjacent its bottom and top ends. A self-contained reactor cartridge unit integrates the vessel cap, electrodes, electrode supports, any electrode wiring connections and any liquid dispersion members into a single removable unit for installation into and removal from the vessel housing so that, when maintenance is required, complete reactor cartridges may be exchanged in a matter of seconds, thereby virtually eliminating downtime of the treatment system for maintenance and other electrode replacement needs.