A method is provided for removing an inorganic ionic species or organometallic ion contaminant, or combination contaminants, including such as arsenic, chromium, bromide, bromate, perchlorate, and/or others from water which contains an unacceptably high concentration of the contaminant(s). The method includes treating the water with an ion exchange resin, preferably a magnetic ion exchange resin such as MIEX.RTM. Resin, which is capable of adsorbing the inorganic ionic species contaminant(s), and regenerating and recycling the ion exchange resin back to the process. The method produces potable water from ground water containing such contaminants and eliminates breakthrough and chromatographic peaking problems observed with conventional ion exchange systems.