Backflushing is something to do occasional. Not everyday on a domestic espresso machine. The process is pretty generic and can be adapted to other espresso machines.

If you don’t clean, your espresso machine, you will gradual discover, that you can’t control the taste of the coffee: different coffees will taste the same, and they will all be more bitter than desired. Furthermore the espresso machines valves won’t work as precise as necessary. The coffee brewing process causes residues of coffee, oils and coffee beans to fasten on surfaces in contact with the coffee. This includes parts inside the machine, where the remains from the brewing process is sucked back when turning off the pump, when ending a brew.  There is nothing you can do to prevent that from happen.

Backflushing – step-by-step

Preparations

There are a few things you need to have in place before you start a proper cleaning process.

You need the following for backflushing:

1. A blind filter. It has the same size and form as the normal coffee filter, you use; but without holes.
2. Espresso machine cleaning detergent. As seen below, I use Puly Cafe Polvere.

Backflushing

The espresso detergent is quite aggressive on oils (to attack coffee oil residues). So make sure it only is exposed to the necessary parts of the machine.

1. Take off the cover of the drip tray, so you can see the drip tray below.
2. Fill the blind filter with one tablespoon espresso machine cleaning detergent, or the amount recommended for the special detergent you use. 
3. Attach the portafilter, with the blind filter and detergent, on the espresso machine, as normal.
4. Turn on the pump, as normal, when brewing a cup of espresso coffee.
5. You hear the pump start, and after 1 – 2 seconds it changes sound. Wait 3 – 5 seconds and turn off the pump. NOT LONGER THAN THAT!
6. You should see excess water, with detergent shortly flush down into the drip tray through the security pipe.
7. The excess water will be brown or black if you haven’t back flushed the machine for a long time.
8. Wait 5 – 10 minutes for letting the detergent work inside the machine.
9. Repeat 2 times, waiting 5 – 10 minutes in between.
10. When you take off the portafilter, it will contain some brown water.

Portafilter wiggle

After  that, you need to clean the fitting between the portafilter and machine.

1. Put a new spoonful of detergent in the blind filter and set the portafilter in place, but don’t fasten it in the tightest position. Hold it with your hand.
2. Engage the pump again, as before; but wiggle the portofilter back and forward, while the water flows over the edge of the filter. Be careful if the water is hot!!! The water will splash.
3. Stop the pump and take off the portafilter.

And now the rinsing

1. Take the drip tray out and rinse it.
2. Rinse the portafilter and blind filter.
3. Attach the empty rinsed blind filter and portafilter to the machine.
4. As before:  Engage the pump. You hear the pump start, and after 1 – 2 seconds it changes sound. Wait 3 – 5 seconds and turn off the pump.
5. Repeat 2 times
6. If the excess water is still dirty, do the whole back slushing process again.

That is the basic backflushing. For completing the cleaning, you also have to rinse the filter and portafilter inside:

Cleaning the portafilter and the filter

1. Put one tablespoon espresso machine cleaning detergent in a small bowl with water. The bowl should be just big enough  to contain the portafilter and the filter. Adjust the amount of detergent according to advise given for your specific detergent.
2. Let the portafilter and the filter stay in the water and detergent for 1 hour, or the night over.
3. Take the portafilter and filter out, and rinse them properly with tap water.

The Rancilio Silvia as new

To be sure that every residues of detergent is gone: brew one cup of espresso with some old beans and throw it out.

If you haven’t been through this cleaning process before, you will experience that your espresso is better and less bitter.

How often?

We use the machine twice every morning for a double espresso, and 6 – 10 times every weekend. My experience is that after a month it’s time to give the Rancilio Silvia a cleaning.