Brackish water desalination ...

Brackish water desalination requires less energy use since the amount of energy needed for reverse osmosis is proportional to the salinity of the source seawater. In addition, the capital costs for brackish desalination plants are relatively lower because they can produce 1.5 to 2.5 times more fresh water from the same volume of saline source water and use lower cost equipment and piping. However, while seawater quality is usually fairly consistent in terms of salinity, brackish water salinity can vary significantly from one source to another and sometimes may require additional treatment steps. Another global disadvantage of brackish water desalination is that it is of limited availability. While over 97.5 % of the planet Earth's water is located in the ocean, the total volume of brackish water is less than 0.5 %. In addition, over 75 % of world's population lives along a coast - so seawater is much more readily available in the vicinity of large coastal urban centers. In most cases however, the use of brackish water for production of fresh water by reverse osmosis desalination is less costly and has a smaller environmental footprint.