There are many water shortage problems currently in the world, some of which are more serious than others. All have different solutions. In several of them membrane technology can make a great contribution since membranes have the ability to produce water of exceptional purity that can be recycled for reuse in a variety of places. This reuse of water already is widely practised in many countries, which reduces net demand on water supply systems. In industry the drive for greener technologies has created the need to reuse more than water to eliminate unnecessary waste. Membranes can often be useful as the recycle stream can usually be much cleaner than with other techniques. Some of the more important syndrome problems for water waste are described, as well as suggested contributions that membranes, and in some cases membrane bioreactors, can make to their solution, both on a small and large scale. They may often contribute to a greener chemistry by controlling mass transfer of reactants and products and enhancing overall yields and conversions. Some examples are given of membrane potential.