Larger scale reverse osmosis water purification units (ROWPU) exist for military use. These have been adopted by the United States armed forces and the Canadian Forces. Some models are containerized, some are trailers, and some are themselves vehicles.
The water is treated with a polymer to initiate coagulation. Next, it is run through a multi-media filter where it undergoes primary treatment, removing turbidity. It is then pumped through a cartridge filter which is usually spiral-wound cotton. This process strips any particles larger than 5 µm and eliminates almost all turbidity.
The clarified water is then fed through a high-pressure piston pump into a series of RO vessels. 90.00–99.98% of the raw water's total dissolved solids are removed and military standards require that the result have no more than 1000–1500 parts per million by measure of electrical conductivity. It is then disinfected with chlorine.