Porous polymeric membranes are used in numerous applications including water filtration systems. Fouling from proteins, toxins, bacteria, and cells present in the water limits membrane utility. Surface modification techniques that retain desired bulk properties while decreasing fouling can effectively extend membrane lifetime. Herein, water vapor plasmas are utilized to create hydrophilic polysulfone ultrafiltration membranes. The permanency of the treatment over two months correlates to covalent incorporation of hydrophilic functional groups into the polymer backbone. Modified membranes show enhanced hydrodynamic characteristics and do not require preconditioning. Thus, water vapor plasma modification provides a potential route to extend ultrafiltration membrane lifetime.