Water containing dissolved salts, such as calcium sulfate, calcium
chloride, magnesium sulfate, magnesium chloride, sodium carbonate, sodium
chloride, sodium sulfate, calcium bicarbonate, and mixtures thereof, is
treated to reduce the concentration of those salts. About 0.1 to about 60
g/L of sodium hydroxide, sodium carbonate, potassium hydroxide, potassium
carbonate, calcium hydroxide, calcium carbonate, aluminum hydroxide,
aluminum sulfate, aluminum potassium sulfate, and mixtures thereof is
added to the water, whereby a precipitate forms in the water. The
precipitate is separated from said water and the water is desalinated
using reverse osmosis, flash evaporation, or another method. The process
is preferably performed by first adding calcium oxide or calcium
hydroxide, separating the precipitate that forms, then adding sodium
hydroxide and sodium carbonate to form a second precipitate.