Disinfection byproducts such as trihalomethanes are commonly found in drinking water. Trihalomethanes are formed upon chlorination of natural organic matter (NOM) found in many drinking water sources. Inspired by molecular CHCl3⊂cavitand host-guest complexes, we designed porous polymers comprised of resorcinarene receptors. These materials show higher affinity for halo-methanes than a specialty activated carbon used for trihalomethane removal. The cavitand polymers show similar removal kinetics as activated carbon and have high capacity (49 mg g of CHCl3). These materials maintain their performance in drinking water and can be thermally regenerated. Cavitand polymers also outperform commercial resins for 1,4-dioxane adsorption, which contaminates many water sources. These materials show promise for water treatment and demonstrate the value of using supramolecular receptors to design adsorbents for water purification.