Maintenance procedure · Written to ASD-STE100 Issue 9 · Formatted to ANSI Z535

Espresso Machine Group Head and Portafilter Cleaning

Semi-automatic machines with a three-way valve — the backflush cycle, the shower screen and the filter basket, and why the descaling powder does not belong in any of them
ApplicabilitySemi-automatic and prosumer espresso machines with a portafilter and a group head. A water-only backflush needs a three-way valve — check your own documentation.
Task time30 min to 50 min editorial estimate, not a measurement
PersonnelOne
Revisionv1 · 2026-08-04
BEFORE YOU BEGIN

Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.

Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.

Summary

Backflushing pushes water back through the group head to clean the valve and the shower screen of built-up coffee oil, using a blind disc that blocks the basket and a cleaning tablet made for the job. It is not the same as descaling, which dissolves limescale out of the boiler with a completely different chemical, and Breville's own documentation is explicit that the two are separate. The portafilter and its filter basket need attention too, and that part applies to every machine: a rinse after use, and an occasional soak when the holes clog with old coffee oil.

Not every espresso machine can run a water-only backflush. The feature needs a three-way valve, and a lever machine typically has none. The button sequence, the cleaning tablet, the soak time and the cycle length are all set by the machine's own maker, and we read manuals from two of them and found real differences even in how long the filter basket soaks. This page gives you the method and the sequence, and sends every one of those specific numbers to your own machine's documentation rather than printing a borrowed one.

Safety

WARNING

DO NOT LET WATER REACH THE POWER CORD, THE PLUG, OR THE INSIDE OF THE MACHINE.
Water on these parts can cause an electric shock.

Necessary equipment

ItemNote
Cleaning toolThe pin on the cleaning tool clears a blocked hole in the filter basket.
Cleaning disc optionalThe cleaning disc has no holes. It is only for the backflush cycle.
Soft clothA soft cloth cleans the group head, the shower screen and the outer housing when damp.
Container optionalA container under the portafilter spouts catches the water from the backflush cycle.
Cleaning tablet materialUse only the cleaning tablet your documentation names for the group head and the backflush cycle.

Look for a backflush cycle

Estimated 2 min

NOTEClean the portafilter and the filter basket only, if your documentation names no backflush cycle for your machine.
  1. Read the documentation for your espresso machine.
    • The documentation names whether your machine has a backflush cycle.
    • The documentation names the cleaning tablet for the cycle.
    1m
  2. Look for a three-way valve statement in your documentation.
    • La Marzocco's three-way valve sends the water from the group head to the drip tray after a shot.
    • A lever machine has no three-way valve and cannot do a water-only backflush.
    1m

Clean the portafilter and the filter basket

Estimated 18 min to 33 min

Filter basket soak time
Unverified — do not rely on this value
CONSULT THE MANUFACTURER DOCUMENTATION FOR YOUR MACHINE FOR THE SOAK TIME

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

WARNING

LET THE GROUP HEAD AND THE PORTAFILTER BECOME COOL BEFORE YOU TOUCH THEM.
These parts stay hot after use and can burn your skin.

  1. Remove the portafilter from the group head.
    <1m
  2. Empty the used coffee from the filter basket.
    <1m
  3. Rinse the portafilter and the filter basket under hot running water.
    • Do this rinse immediately after use. Coffee oil left in these parts can smell bad.
    <1m
  4. Examine the holes in the filter basket for a blockage.
    <1m
  5. If a hole stays blocked, clear the hole with the pin on the cleaning tool.
    <1m
NOTICE

USE ONLY THE CLEANING TABLET YOUR DOCUMENTATION NAMES FOR THIS SOAK.
A different product can damage the machine or leave a taste in your drink.

  1. If holes stay blocked, dissolve the cleaning tablet your documentation names in hot water.
    • Breville names its own cleaning tablet for this soak, for the Barista Express (BES870).
    <1m
  2. Soak the filter basket and the portafilter in the solution, for the time your documentation gives.
    • Breville gives a soak time of about 20 minutes, for the Barista Express (BES870).
    15m
  3. Rinse the filter basket and the portafilter after the soak.
    <1m

Run the backflush cycle

Estimated 7 min to 12 min

NOTEDo this cycle only if your documentation names a backflush cycle for your machine.
Backflush cycle chemical compatibility
Unverified — do not rely on this value
CONSULT THE MANUFACTURER DOCUMENTATION FOR YOUR MACHINE FOR THE CORRECT CLEANING TABLET

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

Backflush cycle activation sequence and duration
Unverified — do not rely on this value
CONSULT THE MANUFACTURER DOCUMENTATION FOR YOUR MACHINE FOR THE BUTTON SEQUENCE AND THE CYCLE TIME

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

  1. Insert an empty filter basket into the portafilter.
    <1m
  2. Place the cleaning disc into the filter basket.
    • The cleaning disc has no holes. Water goes through the group head and back into the drip tray.
    <1m
  3. Place the cleaning tablet your documentation names onto the cleaning disc.
    <1m
  4. Lock the portafilter into the group head.
    <1m
  5. Place a container under the portafilter spouts.
    <1m
WARNING

DO NOT REMOVE THE PORTAFILTER WHILE THE BACKFLUSH CYCLE RUNS.
Hot water flows from the portafilter spouts and can burn your skin.

  1. Start the backflush cycle with the control your documentation names.
    • Breville uses a 3-button sequence for the Barista Express (BES870).
    • Press the 1 CUP button, the 2 CUP button and the POWER button together.
    • Keep the buttons pressed for about 10 seconds, for the Barista Express (BES870).
    <1m
  2. Let the cycle run to the end.
    • Breville gives a cycle time of about 5 minutes, for the Barista Express (BES870).
    5m
  3. Remove the portafilter after the cycle ends.
    • Examine the tablet, for the Barista Express (BES870).
    • Run the cycle again if any tablet remains, for the Barista Express (BES870).
    <1m

Clean the group head and the shower screen

Estimated 2 min

NOTICE

DO NOT USE AN ABRASIVE MATERIAL ON THE GROUP HEAD OR THE SHOWER SCREEN.
An abrasive material can cause damage to these parts.

  1. Wipe the inside of the group head and the shower screen with a damp cloth.
    • This removes ground coffee left in the group head.
    <1m
  2. Insert an empty filter basket and the portafilter into the group head.
    <1m
  3. Press the button your documentation names.
    • Breville uses the 1 CUP button for this flow, for the Barista Express (BES870).
    <1m
  4. Keep the button pressed to send a short flow of water through the group head.
    <1m
  5. Remove the portafilter.
    <1m

Finish the clean

Estimated 2 min

  1. Wipe the outer housing with a soft, damp cloth.
    1m
  2. Install the filter basket and the portafilter, or store them as your documentation directs.
    <1m
  3. Record the date of the backflush cycle.
    • A record of the date shows when the next cycle is due.
    <1m

Terminology

This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.

group head
Also called: grouphead, brew head, brewing head, the espresso head, the shower thing, coffee head
portafilter
Also called: filter holder, the handle, coffee handle, the basket holder, group handle
backflush
Also called: backflushing, back flush, blind flush, espresso machine backwash, reverse flush, cleaning cycle
filter basket
Also called: coffee basket, portafilter basket, the little cup thing, single or double basket, shot basket
cleaning disc
Also called: blind filter, blind disc, backflush disc, blank filter, rubber disc
three-way solenoid valve
Also called: solenoid valve, 3-way valve, group valve, diverter valve
shower screen
Also called: diffuser screen, group head screen, dispersion screen, shower disc

When to use a professional

Do not run the backflush cycle if your documentation names no such cycle for your machine. Some machines have no three-way valve for this cycle.

Stop if water leaks from the group head, the portafilter, or the machine body. Disconnect the machine from the power supply. Speak to the manufacturer.

Do not open the machine body. Do not do work on the three-way valve, the pump, or the boiler. Only a qualified technician must do this work.

Use only the cleaning tablet your documentation names for the group head and the backflush cycle. Do not use a descaling agent for this cycle.

Common questions

What is the difference between backflushing an espresso machine and descaling it?

They clean two different things with two different chemicals. Backflushing pushes water, and sometimes a cleaning tablet, back through the group head and the valve to clear away coffee oil. Descaling dissolves mineral scale out of the boiler with a completely different product. Breville's own instructions are explicit about this: they describe the group-head cycle as "a back-flushing cycle" that is "separate from descaling." Putting a descaling product into a backflush cycle, or a backflush tablet into the boiler, is exactly the mistake this page exists to prevent.

Can I backflush any espresso machine?

No. A water-only backflush needs a three-way valve, the part that sends water from the group head to the drip tray after a shot instead of leaving it under pressure. La Marzocco, which builds this valve into its own machines, contrasts it with a machine that runs on a pump alone, such as a lever machine, and says that kind of machine has no three-way valve. Gaggia's own manual for the Classic Pro describes cleaning the filter and the filter holder by hand, with no backflush cycle mentioned anywhere in it. If your documentation names no backflush cycle, clean the portafilter and the filter basket by hand instead.

What is a cleaning disc, and is it the same as a blind filter?

Yes, they are the same accessory under two common names. It is a solid disc with no holes that sits in the filter basket in place of ground coffee, so water cannot pass through the basket the normal way. Breville's own manual has the reader insert the filter basket, then the cleaning disc, then a cleaning tablet, before locking the portafilter into the group head to start the cycle. Without the disc, a backflush is just a normal shot of hot water with nothing to clean the valve.

Can I use descaling powder to backflush my machine, or vice versa?

No. Every manufacturer we read names a separate product for each job. Breville's own accessory list gives "cleaning tablets" for the backflush cycle and a separate "descale powder" for descaling, as two different items in the box. Gaggia goes further for its own descaling product, warning the reader to "never use vinegar or other descaling agents" in that machine. Route this decision to your own documentation rather than guessing which product goes where.

How often should I backflush my espresso machine?

It depends on the machine and on which of two routines your documentation means. Breville's own tutorial page recommends a plain water backflush "after each brewing session," with no cleaning tablet involved. Separately, the same manufacturer's instruction manual describes a tablet-based cleaning cycle that runs only when a light on the machine tells the reader it is due. These are not the same routine, and we could not read Breville's full video instructions for the first one, so check your own documentation for both.

Why does my portafilter or filter basket smell like old coffee?

Coffee is oily, and that oil clings to metal and turns rancid if it sits for days rather than being rinsed after every use. Breville's own guidance says the filter basket and portafilter should be rinsed under hot water immediately after use to remove residual coffee oil. If the smell persists once the holes are clear, a soak in a cleaning-tablet solution, at the strength and the time your own documentation gives, usually clears it.

Can I put the portafilter or the filter basket in the dishwasher?

Two manufacturers we read both say no, for slightly different reasons. Breville's manual states plainly that no parts or accessories should go in the dishwasher, and that all parts should be cleaned by hand with warm water and a gentle dish-washing liquid. Gaggia's manual goes further for its own filter holder, warning against the dishwasher and against any washing-up liquid or cleaning agent on that specific part, since it can affect the taste of the coffee. Wash by hand, and check your own documentation before using any soap on the portafilter itself.

What if my machine has no backflush cycle at all?

Clean what you can reach by hand. Every machine with a portafilter benefits from a rinse of the filter basket after use and an occasional soak to clear the holes, regardless of whether it has a three-way valve. Gaggia's own manual for the Classic Pro takes exactly this approach: it describes washing the filter and the filter holder and using the manufacturer's own cleaning tablets, without describing a backflush cycle. Skip the backflush section of this page and follow your own documentation for the group head.

Sources

Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.

  1. Tier 1How to Clean an Espresso Machine: A Step by Step GuideBreville USA, Inc. · accessed 2026-07-29 · re-verification due 2027-01-25
  2. Tier 1the Barista Express — Instruction Book (BES870)Breville USA, Inc. · accessed 2026-08-04 · re-verification due 2027-01-31
  3. Tier 1Classic Pro (RI9380) — Operating InstructionsGAGGIA S.p.A. · accessed 2026-08-04 · re-verification due 2027-01-31
  4. Tier 1What Is a 3-Way Solenoid Valve, and How Does It Keep Your Espresso Machine Working?La Marzocco USA · accessed 2026-08-04 · re-verification due 2027-01-31
  5. Tier 1How to Perform a Clear Water Backflush — the Barista ExpressBreville USA, Inc. · accessed 2026-08-04 · re-verification due 2027-01-31

Revision history

Current version 1 · updated 2026-08-04 · next review due 2027-08-04

  1. v1 · 2026-08-04First draft. Sourced to Breville's general cleaning guidance, Breville's own BES870 instruction manual, Gaggia's Classic Pro (RI9380) instruction manual, and La Marzocco's explanation of the three-way solenoid valve, all read on 2026-08-04. No specification publishes as verified: the cleaning tablet, the activation sequence, the cycle time and the soak time are all per-model and route to the reader's own documentation. Brand-specific numbers from Breville's BES870 manual appear in step substeps as a named example only, never as a house figure.

Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.

Comments and corrections

Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.

Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.

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