MAKER'S MARK is one of the few brands to credit Mother Nature for such a unique bourbon taste. That’s because we use pure, iron-free limestone spring water exclusively. Not city, well or river water. Our source is a 10-acre limestone spring-fed lake at the distillery. Maker’s Mark double-distills its whisky — once in an all copper column still to produce what we call low wine and again in a copper pot still to produce high wine. This added step removes impurities and produces a more refined sipping whisky. Our low wine is distilled off at 120 proof, while our high wine is 130 proof.