A high-quality macroporous anion exchange resin, featuring hydrous iron oxide nanoparticles within a polystyrene matrix and a standard Gaussian size distribution. Specifically developed for the removal of arsenate and arsenite, this resin first captures arsenic through ion exchange and subsequently adsorbs it via the iron oxide dispersed within its polymer structure. With rapid kinetics, this resin effectively reduces arsenic levels to below 10 ppb.