Backflushing is the maintenance step most home espresso owners skip — and the one that most directly affects how your shots taste. Old coffee oil in the group head turns good espresso bitter and rancid.
Here is exactly how to backflush, which machines can do it, and how often to bother.
What backflushing actually does
Backflushing routes water through the group without a portafilter basket, dissolving coffee oils and detergents out of the brew head and three-way valve.
Skip it and rancid oils accumulate; shots taste acrid no matter how fresh your beans are.
Which machines can backflush
Any machine with a three-way solenoid valve can — most semi-automatics (Breville, Gaggia, Rancilio). Simple machines with only a switch can often do a water-only backflush.
Many consumer machines instead recommend cleaning with a blank disc. Always follow your manual: forcing a backflush a machine is not built for can break a solenoid.
How often
After heavy use (café-level), daily. For home, weekly is plenty if you use a blind basket plus detergent monthly and water-only weekly.
Listen for changes in shot time or flavour — they are the signal it is time.
