How to Clean and Descale an Espresso Machine

Nobody buys an espresso machine excited about cleaning it. You bought it for the espresso. The cleaning is the price of admission, and ignoring it does not save time. It stores up a problem that arrives as a bitter, rancid background note in every shot, followed eventually by a machine that stops working.

Here is everything that needs cleaning, how often, and how to do it without making it a bigger project than it is.

Why cleaning matters

Two things accumulate inside an espresso machine: coffee oils and mineral scale. They cause different problems and need different solutions.

Coffee oils coat every surface the coffee touches: the portafilter, the basket, the shower screen, the group gasket and the internal pathways. Fresh coffee oils are part of what makes espresso taste good. Old coffee oils go rancid. Rancid oils taste stale, bitter and slightly chemical. They add that flavor to every shot you pull, regardless of how good your beans, grinder and recipe are. If your espresso has a persistent background bitterness that follows you across different beans and grind settings, dirty equipment is a likely cause.

Mineral scale builds up inside the boiler, on heating elements, and in the internal plumbing. It comes from the calcium and magnesium in your water. Scale insulates the boiler (reducing temperature accuracy), restricts water flow (reducing pressure and flow rate), and eventually damages components. Harder water produces scale faster [3]. A machine that is not descaled on schedule will gradually produce worse espresso and eventually need expensive repairs.

Daily cleaning (2 minutes)

This is not really cleaning. It is a habit, like wiping down the stove after cooking. It takes less time than making the coffee did.

After every session

1. Flush the group head. Run water through the group head for 2 to 3 seconds without the portafilter in place. This washes loose coffee grounds off the shower screen and out of the group. Do this after your last shot of the day.
2. Knock out the puck and rinse the portafilter. Knock the spent puck into a container, rinse the portafilter and basket under hot water. Wipe them with a cloth. Do not leave the puck sitting in the portafilter; the moisture and oils will start to go stale.
3. Wipe the steam wand. Purge a short burst of steam to blow out any milk inside the tip, then wipe the wand with a damp cloth. Milk residue that dries on the wand hardens into a crust that blocks the steam holes and is much harder to remove later. Do this immediately after steaming, every time.

Optional but recommended

Leave the portafilter out of the group head when the machine is off. This lets the group gasket decompress and can extend its life. Some people leave it locked in for convenience, and that is fine for the gasket in most machines, but the portafilter will dry with a ring of coffee residue in the basket if you do not rinse it.

Weekly cleaning (10 minutes)

Backflushing

Backflushing is the most important regular cleaning step. It cleans the three-way solenoid valve and the internal pathways that a simple flush does not reach.

You can only backflush machines with a three-way valve. Most machines with an E61 group head, most prosumer machines and many mid-range machines have one. Some entry-level machines (particularly those with a simple OPV and no three-way) do not. Check your manual. If your machine does not support backflushing, skip this step and focus on soaking the basket and wiping the shower screen.

How to backflush:

1. Insert a blind basket (a basket with no holes, sometimes called a backflush disk) into the portafilter.
2. Add an espresso machine cleaning tablet or a small amount of espresso machine cleaner powder to the basket. Use the product and amount your manufacturer recommends.
3. Lock the portafilter into the group head.
4. Run the pump for 10 seconds. The water will pressurize against the blind basket and push backward through the three-way valve into the drip tray.
5. Stop the pump for 10 seconds.
6. Repeat the on/off cycle 5 to 6 times.
7. Remove the portafilter, rinse the blind basket, and flush the group head with clean water for 10 seconds.
8. Run two or three more on/off cycles with just water (no cleaner) to rinse the internal pathways.

The water that comes out during backflushing will be brown and oily. That is the old coffee residue you are removing. If it is very dark or has chunks, it has been too long since the last backflush.

Soaking the basket and portafilter

Remove the basket from the portafilter. Drop both into a container of hot water with a cleaning tablet dissolved in it. Let them soak for 15 to 20 minutes. Rinse thoroughly. The basket holes will be visibly cleaner and water will flow through them more evenly.

Wiping the shower screen

Remove the shower screen (usually held by a single screw in the center of the group head) and wipe it clean. If there is a rubber gasket behind it, wipe that too. Reassemble. This takes two minutes and makes a noticeable difference if you have not done it in a while.

Monthly to quarterly: descaling

Descaling removes mineral scale from the boiler, heating elements and internal plumbing. How often depends on your water hardness:

Water hardness	Descaling frequency
Soft (under 75 mg/L TDS)	Every 4-6 months
Medium (75-200 mg/L TDS)	Every 2-3 months
Hard (over 200 mg/L TDS)	Every 1-2 months

How to descale

Use the product your manufacturer recommends. Most manufacturers sell or recommend a specific descaling solution. Citric acid solutions are common and generally safe for most machines. Vinegar is acidic enough to damage some seals and gaskets and can leave a taste that is very hard to rinse out. Most manufacturers explicitly advise against it [1] [2].

The exact process varies by machine, but the general steps are:

1. Empty the water tank.
2. Mix the descaling solution with water according to the instructions and fill the tank.
3. Run the solution through the machine according to the manual. This usually means running water through the group head and the steam wand in intervals, letting the solution sit in the boiler for a period, and then flushing.
4. Rinse the tank thoroughly.
5. Run at least two to three full tanks of clean water through the machine (group head and steam wand) to flush all the descaling solution out.
6. Taste a small amount of the flush water before pulling a shot. If it tastes like anything other than water, flush again.

Do not skip the rinse. Descaling solution left in the machine will end up in your espresso. It tastes exactly as bad as it sounds.

Signs your machine needs cleaning

• A persistent bitter, stale or rancid taste that does not change with different beans or grind settings.
• Slow water flow from the group head (scale restricting the pathway).
• The machine takes longer to heat up than it used to (scale insulating the boiler).
• Visible residue on the shower screen, basket or portafilter.
• The steam wand is weak or blocked (milk residue or scale in the tip).
• Brown or dark water during a backflush, especially if you have not done one recently.

The time math

Daily cleaning: 2 minutes. Weekly backflush: 10 minutes. Descaling every 2 to 3 months: 30 minutes. Total per month: about an hour. For a machine that costs $300 to $1,000 and can last a decade with proper care, this is not a bad trade.

A clean machine pulls better shots, lasts longer and costs less to repair. That is the whole argument, and it is enough.

Caffeine, heat and your machine. The FDA says up to about 400 mg of caffeine a day is not generally associated with negative effects for most healthy adults; pregnancy, some heart conditions, anxiety, reflux and certain medicines can change that, so check with a clinician if any apply. Steam wands and group heads are hot enough to burn. Unplug and cool a machine before opening or cleaning it, and follow the manufacturer’s descaling instructions.

Related reading: Water for Coffee: The Boring Variable That Changes Everything | Espresso Machines Under $500: What to Buy First