Coffee is oily, and those oils go rancid. They collect in the group head, the shower screen, the basket and the portafilter spouts, and within a couple of weeks they make every shot taste bitter and stale no matter how fresh the beans are. Cleaning is not about appearances. It is about taste.
Every day
- Steam wand: wipe it with a damp cloth and purge it immediately after every single milk drink, before the milk dries. A cloth kept only for the wand, never for the bench.
- Group head: knock out the puck, run the group for two seconds to flush, and wipe the shower screen and the gasket with a brush.
- Portafilter: rinse it, but do not leave it soaking in the group all day full of old coffee.
Backflushing, weekly at home and daily in a cafe
Backflushing forces water back through the group head and out through the drain, taking the built-up oils with it. It only works on machines with a three way solenoid valve, which means most commercial machines and most prosumer ones. If your machine does not have one, and many single boiler home machines do not, skip this and soak the parts instead.
- Put the blind basket, the one with no holes, into the portafilter.
- Lock it in and run the pump for about 10 seconds. You will hear the pressure build and release. Stop, wait 10 seconds, repeat about five times. That is a plain water backflush, and it is enough for daily use.
- Once a week, add half a teaspoon of espresso machine cleaning powder to the blind basket and repeat the cycle.
- Then rinse: repeat the whole cycle with plain water at least five more times, remove the basket, and flush the group for 10 seconds. Any detergent left in there will ruin the next shot.
Weekly soak
Drop the baskets, the portafilter, and the shower screen if it comes off, into a jug of hot water with the same cleaning powder for 20 minutes. Do not put the portafilter handle in: the heat and detergent will dull the plastic or wood, so let only the metal sit in the solution. Scrub with a brush, rinse thoroughly, and you will see how much brown comes out even from a machine that looked clean.
The steam wand, properly
Milk that has dried inside the tip needs soaking, not scraping. A milk line cleaning solution in a jug, with the wand submerged and the steam on briefly, then purged through, clears the tip and the internal line. Milk residue inside a wand is a food safety issue, not just a taste one.
Do not confuse this with descaling
This routine handles coffee oil and milk residue. It does not touch the mineral scale inside the boiler, which needs a different product and a different schedule. See how to descale an espresso machine.
And if the shots have gone bad but the machine is spotless, the problem is more likely the grind. Start with the coffee grind size chart.
