Climate change and industrial pollution threatens the availability of clean water. Although established protocols of water treatment exist, water capture by porous materials has emerged as a viable alternative to energy intensive processes. Here we introduce a new charged porous polymer that is capable of capturing and releasing water by simple humidity or temperature swings. The quaternary amines on the framework structure attract water molecules and further solvate by coordination. The porosity of the network structure also provides enough void where water can diffuse throughout the solid. Water uptake capacity of the porous polymer surpasses common desiccants like silica gel and molecular sieves, and has the potential to act as an organic desiccant in applications like electronics or food packaging.