Abstract: A method of treating contaminated water that has ferrous ions and at least one additional mineral in solution includes the steps of: adding a sufficient quantity of a caustic agent to the contaminated water to achieve a basic pH, and adding oxygen to the contaminated water to achieve a molar ratio of oxygen to ferrous iron of at least 1:10. The pH and the oxygen concentration are sufficient to produce ferrous hydroxide (Fe(OH)2) from ferrous ions and ferric hydroxide (Fe(OH)3) from the ferrous hydroxide while limiting colloidal iron formation, at least the ferric hydroxide forming a precipitate. The precipitate is separated from the contaminated water.