You can't even start to discuss the bad flavors of espresso when you are using dirty equipment. Every cup will have a distinct taint if the grouphead and the portafilters have rancid coffee residue. We sell Urnex Cafiza Espresso Machine Cleaner in tablet form or in 20 oz. bottles of powder. It is a specially formulated powder detergent for the heavy residues that accumulate in the espresso machine grouphead, water lines and valves.
While Cafiza is made to be used with automatic pump machines that can be back-flushed (i.e. they have a 3 way valve), it is an important cleaning solution for ANY espresso machine owner to have. It can be used simply to clean the portafilter and filter baskets and to soak any removable part of the machine that gets dirty. I use it to clean the tank on my Pavoni, which I then invert the machine to drain. Before cleaning, consult your machine's original instructions. The retail package contains eight 2 gram tablets. It is designed to be used on super automatic espresso machine but works equally well on semi-automatic ones, whether they backflush or not. You can also use it to clean french press parts. I use the tablets for cleaning other parts too, dissolving them first to create a full-strength solution. Do not use Cafiza on aluminum espresso parts, such as aluminum Moka Pots. (You can use them on the Moka Pots we sell; they are all stainless steel).