Zeolites are promising adsorbents for CO₂ adsorption both for DAC as well as point sources due to their high volumetric capacity, as well as the tunability afforded by their exchangeable cations and microporous framework structure. However, the presence of water (unavoidable for a postcombustion gas mixtures as well as DAC where water is typically a thousand-fold higher in concentration compared to CO₂) causes competitive adsorption that significantly diminishes CO₂ adsorption capacity of zeolites. Our research addresses the rational design of selective CO₂ binding sites in zeolites. This is an uphill battle (water adsorbs to zeolites with 7.5 kcal/mol higher bonding energy compared to CO₂), and one that is underrepresented in the literature (about 1.5% of published manuscripts dealing with CO₂ adsorption in zeolites make mention of water as a multicomponent adsorbate), but one that promises large possible benefits in terms of decreasing the capital and energy costs associated with predrying gas mixtures prior to adsorption. In this presentation, focusing on examples from three small-pore zeolite frameworks possessing double 8 membered rings (D8Rs), consisting of RHO, MER, and PAU, we demonstrate the D8R as a highly proficient CO₂ adsorption site, which can favor the adsorption of CO₂ over water (at up to 10% relative humidity) under thermodynamic control. This is enabled by cooperativity between CO₂ and water, which is manifested in CO₂ thermodynamic adsorption amounts that are higher under wet compared to dry conditions. We discuss this cooperativity from the standpoint of a structure derived from Reitveld refinement of PXRD data. Combining gravimetric analysis with IR spectroscopy, our data highlight this cooperativity in terms of water being able to facilitate stronger interactions between CO₂ and cations in the D8R, while also unequivocally demonstrating sites in which CO₂ adsorption causes the desorption of water. These results motivate work in the ultimate quest of a selective zeolitic CO₂ adsorbent, which treats water as just another light gas, obviating the need for drying pretreatment.