Reverse osmosis water purification unit

A reverse osmosis water purification unit (ROWPU) is a portable, self-contained water treatment plant. Designed for military use, it can provide potable water from nearly any water source. There are many models in use by the United States armed forces and the Canadian Forces. Some models are containerized, some are trailers, and some are vehicles unto themselves.

Each branch of the United States armed forces has their own series of ROWPU models, but they are all similar. The water is pumped from its raw source into the ROWPU module, where it is treated with a polymer to initiate coagulation. Next, it is run through a multi-media filter where it undergoes ion exchange. It is then pumped through a cartridge filter which is usually spiral-wound cotton. This process clarifies the water of 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 vessels where it is subject to reverse osmosis. The product water is free of 90.00–99.98% of the raw water's total dissolved solids and by military standards, should have no more than 1000–1500 parts per million by measure of electrical conductivity. It is then disinfected with chlorine and stored for later use.

Within the United States Marine Corps, the ROWPU has been replaced by both the Lightweight Water Purification System (LWPS) and Tactical Water Purification Systems (TWPS). The LWPS can be transported by Humvee and filters 125 gal per hour. The TWPS can be carried on a Medium Tactical Vehicle Replacement truck, and can filter 1200 to 1500 gal per hour.