A first method for determining an amount of water in a sample includes the step of providing a reagent including: sulfur dioxide or a derivative thereof; a base; an optional hydrogen halide or hydrogen halide donor; a solvent; and a sulfonic acid; and the step of titrating the sample with the reagent. A second method for determining an amount of water in a sample includes the step of providing the aforementioned reagent, combining the sample with the reagent; and adding a source of iodine to the sample and/or the reagent. The reagent may alternatively consist essentially of sulfur dioxide or a derivative thereof; imidazole and/or a derivative thereof; an optional hydrogen halide or hydrogen halide donor; acetonitrile; methane sulfonic acid; and methanol and/or ethanol.