A method for the rapid dilution of an aqueous peracid solution, particularly, peracetic acid, in which a concentrated peracid solution is diluted with an aqueous diluent to produce a more dilute peracid solution in which the solution components are already at equilibrium immediately after dilution. The peracid in a preferred embodiment of this method is peracetic acid, for which the aqueous diluent is acetic acid and water, or hydrogen peroxide and water, or acetic acid, hydrogen peroxide and water, whose relative amounts are selected to produce a diluted aqueous peracid acid solution whose peracetic acid, hydrogen peroxide and acetic acid components are in equilibrium immediately after dilution.