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Taken directly from the website, they recreate the water. In their words: "By using our proprietary water treatment system, known as “Brooklyn Water Works,” The Original Brooklyn Water Bagel Co.® can successfully replicate the natural composition of the water that flows through the Catskill Mountains in upstate New York into the homes of Brooklyn residents. This replication is accomplished by filtering local water down to its purest, most natural state, and then adding unique elements found only in our water."