That is a difficult question to answer. It depends on the water source, the time of year, and how much water is in 1.5 cups. In general, it takes about 3 cups of water to fill up a standard American drinking cup. That means that if you use 1.5 cups of water for every 1 cup of coffee that you drink, you would need to use about 8 cups of water to make up for one cup of coffee that you would use in a single serving.
