I used to use 100% distilled water until a couple of people suggested that I mix it with a bit of bottled mineral water. I tried it, and you know what? The espresso didn’t taste as “flat.” The shots also taste a bit sweeter Before each session, I now mix a batch of 80% distilled water with 20% Vittel in a plastic water container. Then, I close the lid and shake vigorously for about 30 seconds in order to aerate the water before putting it into the Pavoni. This may sound a bit fanatical, but it works for me. Just remember, your coffee can only be as good as your water. Sometimes I will put the filter in and pull a shot without any coffee just to taste the water. This way, I can tell if the water tastes OK as well as whether the equipment is clean enough.