在膜过滤方法中，一种膜孔径尺寸大致在1.5纳米到0.2微米范围内的过滤，其过滤动力为液体的压力差，过滤机理是通过膜孔筛除作用进行分离。

超滤技术已运用在便携式水壶中，其一为过滤薄膜孔径约15纳米的LIFESAVER救命水壶。

Ultrafiltration (UF) is a variety of membrane filtration in which forces like pressure or concentration gradients lead to a separation through a semipermeable membrane. Suspended solids and solutes of high molecular weight are retained in the so-called retentate, while water and low molecular weight solutes pass through the membrane in the permeate. This separation process is used in industry and research for purifying and concentrating macromolecular (10 - 10 Da) solutions, especially protein solutions. Ultrafiltration is not fundamentally different from microfiltration. Both of these separate based on size exclusion or particle capture. It is fundamentally different from membrane gas separation, which separate based on different amounts of absorption and different rates of diffusion. Ultrafiltration membranes are defined by the molecular weight cut-off (MWCO) of the membrane used. Ultrafiltration is applied in cross-flow or dead-end mode.