A system for removing cyanotoxins and excess ions from contaminated water. Contaminated water passes from a storage tank (200), through a sand filter (210), through a reaction chamber (230), and finally through a carbon filter (270). The sand filter removes particulates and bacteria. The reaction chamber first destroys cyanotoxins, algae, and bacteria through the use of high voltage shocks applied between two groups of electrodes (285, 285′ then the voltage on the electrodes is lowered and electrolysis is used to sequester free ions in the water in the region near the electrodes. Partially treated water is removed from the upper portion of the reaction chamber and passed through a carbon filter (270) to remove radiation, and improve taste and smell. The water is then potable. The water remaining in the reaction chamber is discarded into a reservoir (265).