The development of nanofiber technology offers viable means to produce nanofibrous articles, useful for many health, energy and environmental applications. In specific, polymeric nanofibers fabricated by electrospinning can be used as effective membrane materials for environmental remediation due to the light weight, high surface area, and interconnected porous structure. In this paper, we review some recent advances in electrospinning for mass production of nanofiber membranes, especially suitable for water purification. These electrospun nanofibers not only can form highly porous membranes with controlled pore size, but also can be functionalized to enhance the separation performance. Various composite membrane formats containing different arrangements of nanofibers have been demonstrated for many sorts of water applications, including microfiltration, ultrafiltration, nanofiltration, reverse osmosis, membrane distillation, and adsorption.