Purification cannot be performed by simple distillation due to formation of an azeotrope with water, although initial drying of the solvent containing large amounts of water is performed by adding benzene to form a tertiary azeotrope and distilling off the water. Smaller amounts of water are removed by drying with calcium oxide (CaO), potassium carbonate (K2CO3), calcium sulfate (CaSO4), or magnesium sulfate (MgSO4), followed by fractional distillation. Anhydrous tert-butyl alcohol is obtained by further refluxing and distilling from magnesium activated with iodine, or alkali metals such as sodium or potassium.