Water scarcity is a global problem. Although reverse osmosis is an effective method for water purification, it is costly and energy intensive. To address this issue, previously, biomimetic membranes have been developed that are embedded with aquaporins (AQPs) or artificial water channels (AWCs). We designed and synthesized helical amphipathic oligourea foldamers as a new class of AWCs that can be a promising alternative to AQPs. Our foldamer monomers do not have a tubular structure, but they self-assemble, generating void space that acts as transmembrane channels, which exhibit selective water permeability. The crystal packing of one of these foldamers shows a porin-like superstructure with a hydrophilic pore of 4.8 Å diameter. The known resistance of oligoureas to proteolytic degradation suggests that they offer long-term stability. Sequence-based tunability of their properties along with their large-scale synthesis can make them a new class of AWCs for water purification.