Espresso Machine Cleaning Steps: How Long Should Backflushing Take?

Baristas have all run into this problem: you dial in the espresso parameters in the morning, but by noon they no longer hold, and the flow rate has slowed noticeably.

FrontStreet Coffee has previously explained two situations that cause this. The first is on rainy days, when the air humidity is high, the beans in the hopper absorb moisture easily, and during grinding they are also affected by water vapor, so the grounds clump, the flavor dulls, and extraction becomes unstable.

The second is when the parameters are set with the original beans in the morning, but fresh beans are added to the hopper in the afternoon, which means the extraction parameters need to be dialed in again.

If neither of those applies, though, there may be another reason: the espresso machine is too dirty inside.

When you extract coffee, a small amount of grounds gets sucked back into the group head. After long-term daily use, coffee residue builds up inside the group head, which can obstruct the water outlet, making the flow slower and less stable. The accumulated residue also affects water quality, producing undesirable flavors in the cup.

So before switching off the machine each day, it is necessary to clean the inside of the group head. This is done with a procedure called backflushing. First, use a blind filter, which is a portafilter basket without filter holes. That way the water released from the group head has nowhere to go and must return through the internal pipes, washing away the coffee residue left there.

The specific operation is to fit the blind filter into the portafilter handle, just as you would for extracting coffee, and lock the portafilter onto the group head.

Then press the extraction button for 10 seconds, and the pressure relief outlet will discharge wastewater containing coffee residue.

When you remove the portafilter, a small amount of wastewater with coffee residue will also be sitting in the blind filter.

Next, empty the wastewater from the blind filter, reattach it to the group head, and repeat the previous steps until the water in the blind filter runs clear. Generally, repeating this 5 times achieves that result.

Some baristas might object: "I already backflush every day when I close, so why are my extraction parameters still unstable?" The answer is that it is not being cleaned thoroughly enough. Some coffee residue is more stubborn and hard to remove with plain water backflushing, which is where coffee machine cleaning powder comes in.

The method is to first pour 2-3g of cleaning powder into the blind filter, then attach it to the group head, press the extraction button, and stop after 5-7 seconds. At this point the pressure relief outlet sprays white wastewater containing coffee residue.

Remove the portafilter, and the blind filter will hold water-soaked cleaning powder and coffee residue. Tilt it gently to pour out the water and residue while keeping the soaked cleaning powder, reattach it to the group head, press the extraction button for 5-7 seconds, then remove the portafilter and empty the water from the blind filter, and reattach it to the group head, until the cleaning powder in the blind filter disappears when you remove the portafilter. Generally, repeating this 4-5 times is enough.

Next, flush the group head without a portafilter and gently brush the shower screen and gasket. After cleaning the blind filter, reattach it to the group head and repeat the water backflushing steps, this time to make sure all the cleaning powder inside the group head is flushed out. Generally, repeat this about 7-10 times.

The frequency of cleaning-powder backflushing does not need to be high. Typically, perform water backflushing daily and cleaning-powder backflushing weekly.

FrontStreet Coffee Recommendation

A machine that is clean inside pulls a cleaner shot, and a cleaner shot makes the differences between beans far easier to taste. For a Dirty, which is really just an iced latte without the ice, you want a medium-dark blend or SOE whose caramel sweetness contrasts with cold milk. For consistency and value, FrontStreet's Classic Blend combines smooth Brazilian coffee with wild Mandheling and a touch of Robusta, so it extracts with a rich, fine crema and, in a Dirty, brings out butter and roasted chestnut aromas.

Another strong option is FrontStreet's PWN Golden Mandheling SOE. Its standard is 18 screen and above with fewer than 3 defective beans per 300g green sample, placing it in the top G1 grade, dark green in color and neatly flat in shape, and it undergoes three rounds of hand sorting to guarantee a clean cup. Roasted medium-dark, it shows caramel, dark chocolate, and toasted bread notes that pair beautifully with milk, so a Dirty tastes like iced creamy cocoa.

If you prefer a smaller contrast and a fresher flavor, the medium-roast Strawberry Candy Espresso is a good match for ice and milk, offering rose, grape, raisin, and nut aromas that turn into cranberry cookie and hazelnut ice cream notes in a Dirty.