Many people think that bodies of water can only be classified as either ‘fresh’ or ‘salt’, with the former existing in limited quantities at any given time. True enough, it is often said that only 0.5 percent of the Earth’s freshwater supply is readily accessible, while the remaining 99.5 percent is either held in glaciers and icebergs or in bodies of saltwater deemed unfit for human consumption.
Saltwater and freshwater can meet halfway to form bodies of ‘brackish’ water where salt levels are higher than freshwater though lower than saltwater. In the United States, the majority of inland water sources—such as coastal areas (like estuaries), aquifers, and surface waters (like marshes)—are classified as brackish water. At present, brackish waters are one of the Bureau of Reclamation’s points of interests when it comes to augmenting the country’s water supply.
These days, water companies utilize at least four methods to purify brackish water and produce drinking water of acceptable quality: reverse osmosis, electrodialysis, multistage flash distillation, and multieffect distillation. Among the four, reverse osmosis is the most popular and preferable because it consumes fewer energy, requires lesser maintenance, and can be performed using one system (in theory), as evidenced by numerous water filtration efforts in the Caribbean.