Desalinated water be needed where are lack of fresh water, such as people works on marine (boats, drilling platforms etc.). residents on islands and coastal areas.
The largest amount of desalinated water are produced for municipal sector, however, industries such as power generation have the greatest number of desalination facilities.
Total worldwide installed capacity by user type – DesalData.com
The raw water be desalinated not almost sea water, there are still several kind of water can be desalinated. Their TDS usually lower than sea water. such brackish water ( at desert), river water, well water etc. Since 2003, the demand for large seawater desalination plants has grown significantly. Seawater now accounts for almost two-thirds of all feed water.