Since your coffee is over 98% water, it makes sense that the quality of the water will impact the taste. One of the subjects regularly bandied about in the home espresso world is if there is a significant impact on one’s shot if using a machine that has a separate brew boiler — especially if the machine isn’t pulling a lot of shots regularly and the water has a chance to sit for awhile in that boiler.
We have spoken with folks on both sides of the ‘divide': Those that think the water goes stale in the brew boiler so that a heat exchange provides a cleaner, fresher taste and those that think the temperature control and performance differential you get from a double boiler outweighs any concerns of water flavor.
So we asked Gail to perform a practical test for us on the La Spaziale Mini Vivaldi: We dialed in our shot and then let the machine sit for a couple of days. Then we pulled shots with the water in the reservoir and boiler and shots with fresh water in the reservoir and a completely flushed brew boiler. Watch and find out the results.