Bring the water to a boil in a nonreactive saucepan with a tight-fitting lid. Remove from the heat, whisk in the espresso, cover and allow to steep for 10 minutes. Strain once to eliminate most of the grounds, then strain through a coffee filter or dampened napkin or paper towel to eliminate all the remaining grounds. Measure the coffee: there should be 3 cups. If not, add water to make 3 cups.