Espresso is at least 88% water.
Drip coffee is at least 98% water.
A small adjustment in the content of just one mineral in the water can affect the flavor of your drink more than the origin, roast, or quality of the coffee beans.
Madison City water comes from wells and the Tennessee River. The wells produce hard water because of limestone in the aquifer. The river produces softer water but with higher turbidity and and other contaminants from runoff. The raw water quality changes with rainfall, seasonal changes, and the source, so the treatment facility has to respond to changes in the raw water quality to produce fairly consistent water. The utility does a good job keeping all contaminants well below the EPA’s maximum levels considered safe. Safe water may not taste good. And safe water might taste differently from one hour to the next or even one part of town to the other (because the water is constantly reacting with the pipes, valves and anything it touches).
So we filter the water with reverse osmosis (which removes about 90% of all minerals from the water). Due to this filtration process, reverse osmosis (RO) water is “hungry” for minerals and will dissolve the metal from the pipes and espresso machines. RO water is also has very little buffering capacity to counteract the acidity of the coffee and tends taste flat and insipid. So we run the water through a remineralizing filter to add exactly the right amount of good minerals. These added minerals react with the coffee grounds to get a stronger, richer extraction with less bitterness or acidity.
– Joel Florian
(Owner & CEO of Creme Brew Lait)