Covalent organic frameworks (COFs) are highly porous crystalline organic polymers with strong covalent bonds, making them ideal for developing advanced separation membranes. Significant progress has been made in the fabrication and functionalization of COF membranes over the last six years, particularly in thin-film, composite, and mixed matrix membranes. These membranes have shown effective rejection of organic dyes and model organic foulants, as well as salt rejection in desalination applications. However, the ordered structure and separation mechanisms of COF membranes remain unclear and debatable. This perspective critically analyzes the design and exploitation of COFs for membrane fabrication and their performance in water treatment applications. It highlights technological challenges associated with COF properties, fabrication methods, and treatment efficacy to guide future research efforts towards realizing highly selective separation membranes for scale-up and industrial applications. The article discusses the engineering of intrinsic properties of COFs, such as pore size and surface charge, and the challenges in fabricating high-quality crystalline membranes. It also evaluates the processability of COFs into membranes, including in situ growth, interfacial polymerization, blending, and incorporation into conventional thin-film nanocomposites. Finally, it assesses the performance of COF membranes in water treatment, focusing on permselectivity and the removal of organic pollutants and salts.Covalent organic frameworks (COFs) are highly porous crystalline organic polymers with strong covalent bonds, making them ideal for developing advanced separation membranes. Significant progress has been made in the fabrication and functionalization of COF membranes over the last six years, particularly in thin-film, composite, and mixed matrix membranes. These membranes have shown effective rejection of organic dyes and model organic foulants, as well as salt rejection in desalination applications. However, the ordered structure and separation mechanisms of COF membranes remain unclear and debatable. This perspective critically analyzes the design and exploitation of COFs for membrane fabrication and their performance in water treatment applications. It highlights technological challenges associated with COF properties, fabrication methods, and treatment efficacy to guide future research efforts towards realizing highly selective separation membranes for scale-up and industrial applications. The article discusses the engineering of intrinsic properties of COFs, such as pore size and surface charge, and the challenges in fabricating high-quality crystalline membranes. It also evaluates the processability of COFs into membranes, including in situ growth, interfacial polymerization, blending, and incorporation into conventional thin-film nanocomposites. Finally, it assesses the performance of COF membranes in water treatment, focusing on permselectivity and the removal of organic pollutants and salts.