Microfiltration and ultrafiltration membranes are barriers that act as filters, retaining particles and molecules larger than their pore size while allowing smaller ones to pass through. It is important to characterize membranes in terms of pure water permeance before using them in separation processes since it enables the comparison of performance between similar samples, and it helps assess fouling after filtration. Here we outline a protocol for evaluating the pure water permeance of ultra- and microfiltration membranes.