Backflushing - How do you do it?

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For this you need a blind filter basket (the one with no holes). You place either a powder or a tablet within the blind filter (e.g. Puly Caff) and is backflushed according to the instructions supplied with the product. I think it's best to backflush when the machine is hot. The basic backflushing procedure is quite simple and is designed to flush cleaning solution back up into the grouphead, through the preinfusion and pressure release valve. It finally vents into the drip tray, but during this journey, the cleaning solution reaches all parts of the group that get exposed to coffee and can remove coffee deposits and other unwelcome material.


The procedure:

  1. Place blind filter basket in your portafilter holder
  2. Place cleaning product in blind filter (for Puly Caff I only use a level teaspoon)
  3. Load the portafilter with blind filter securely into the group.
  4. Move Coffee brew lever up for about 20-25 seconds
  5. Move Coffee brew lever fully down (slowly) to depressurize the group, cleaning solution will vent into the drip tray (this is the actual backflush)

Repeat 4 & 5 about five more times. I recommend waiting about 20-30 seconds between each backflush.

NB: have a cloth handy, watch the portafilter handle closely, if you see it begin to move clockwise (coming unlocked), cover with cloth and immediately move the coffee brew lever down to release the pressure. DO NOT attempt to hold it in place, you will not be able to do so and risk scalding and/or the cleaning product entering your eyes!

After this remove the portafilter run around 50ml of water through group, then reload the "rinsed" blind filter and do 3-5 pure water backflushes and then remove portafilter and repeat this clean water process.

If the solution was particularly dirty (or the foam coming out of the group does not turn white, but stays brown), you may want to repeat the whole process, unless the instructions with the cleaning product advise against this. Your Coffee Brew lever may squeak and become stiff while doing this and although this is only temporary, I recommend you use a suitable food safe lubricant on the cams in the E61, see e61-lubrication. Pull a shot to “cure” the group, some people say to throw this away, but that's up to you and how frugal you feel.

At this time I usually remove the shower screen and give it a good clean with a group head brush, many deposits accumulate behind this screen and they are often not fully removed by backflushing. It's also a good idea to brush the dispersion screen (the brass bit under the shower screen). Use a little Puly Caff dissolved in boiling water for these tasks. This is especially important if the water is coming evenly in a shower type pattern from the shower screen when you draw water from the group with no portafilter loaded. Important With a HX machine they often run quite hot and the very high temperature water will tend to "pull together", so either check this when the machine is cold, or flush plenty before checking.

Note: Backflushing with cleaner is not limited to manual or automatic E61 groups, but you should always check your manufacturers machine specific instructions before backflushing a particular machine. I personally believe that any machine that uses either an electric 3 way solenoid valve or manual e61 lever valve (that causes the group to depressurise after making a coffee) needs to be backflushed with cleaner. There are some cheap machines on the market that use a spring sealing mechanism (preset to around 4 bar) to either force water through the coffee, or if a hot water valve is opened allow water to flow through the hot water wand….these cannot be backflushed. Lever operated machines where a lever is pulled to create pressure to force water through coffee (this can be via compression of a spring), also cannot be backflushed.