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How To Clean Your Coffee Machine – The Day to Day Basics

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Dean Cartwright

09th Nov 2021

8 minutes for reading

When the Cartwright Coffee engineers are out and about, they often come across espresso machines that are not being cleaned correctly. As this article will reveal, sometimes the mistakes are caused by staff or owners looking to be efficient or not fully understanding the way their machines work.

Incorrect or infrequent cleaning can lead to a host of problems, from unnecessary service call outs and poor tasting drinks to unsightly equipment and even health and safety concerns.

I’ve written this article to help coffee shop owners, bars, restaurants and staff members understand how to clean their espresso machines effectively while avoiding the common mistakes we come across in the field.


Throughout the day, as your staff pull shot after shot, coffee moves up into the group heads of your machine. Oils, resins and old grinds quickly build up inside and if you don’t backflush regularly, you will start to notice a burnt smell. As your fresh water filters through this mixture of ash and oil, it impacts the flavour of the coffee.

This is why you really should be backflushing your espresso machine every day.

The role of backflushing is to circulate cleaner up into the group heads so that it reaches behind the shower attachment and into the three way valve. This removes the resins, oils and burnt grinds to ensure your customers continue to enjoy a fresh, tasty coffee.

Since 2004, my machine cleaner of choice has been Puly Caff. This is an effective product which contains clear, detailed guidance for usage on the side of the pack. This is really useful for staff who may forget how to clean your coffee machine correctly.

Here are my step-by-step instructions for backflushing your machine:

  1. Remove the portafilter basket and replace it with a blind filter.
  2. Add three to five grammes of Puly Caff powder to the portafilter (if you have one of our Speciality Group Head Cleaning Brushes, you can use the scoop on the back for consistency).
  3. Press the ‘Double Cup’ button once. Why this button? Because it is the easiest button to identify by icon and position (it’s usually the middle button). It also avoids the risk of leaving the water running continuously. Trust me; this tip will come in handy when training new staff.
  4. Count silently for ten seconds and then push the button again to stop the water (you can count out loud but people might give you funny looks).
  5. Wait for five seconds. This will allow the detergent to work its magic inside the group head.
  6. Repeat steps three to five at least five times.
  7. Repeat all steps from 1 to 6 again without cleaner to flush your coffee machine with water.

During this process, the cleaner is discharged through the three-way valve and out into the drip tray. Sometimes people think something is going wrong when they see brown water coming out into the drip tray but this is what’s meant to happen during backflushing.

Next, rinse the detergent out of the portafilter and repeat the entire process. This is for health and safety reasons. While the detergent won’t kill your customers it can upset their stomachs so this second cycle will wash out any detergent still inside the group heads.

Important note:

Do not backflush multiple group heads at once.

We have sometimes been called out to machines which are ‘leaking’ only to find out that the baristas have tried to save time by backflushing two or even three group heads at the same time. Why is this a problem?

Well, under the drip tray is a waste tray which funnels water into the mains waste. These waste trays usually measure 10 or 15cm x 10cm x 5cm deep (or less than 10cm in diameter if circular). Backflushing multiple group heads will overload the waste tray and the water will spill out under the machine. Save yourself an unnecessary call out charge by backflushing your group heads one at a time.

PS. We also recommend not removing the drip tray. If you do choose to remove it, use heavy gloves to protect yourself from sharp edges. Don’t put your drip tray into the dishwasher because it is made from stainless steel and will be damaged by any corrosive chemicals you may be using.

Portafilter care

We also recommend you soak your portafilters in a suspension of cleaner at least once a week, daily if you’re a high output business. The cleaner will get to old coffee grounds hidden inside the spouts.

Use a deep, narrow container like a kitchen measuring jug so you can stand the portafilters upright with the handles at the top.

Remove the coffee baskets first and, if necessary, use a nylon group head brush to dislodge the worst of the old coffee. Fill the container with hot tap water but take care not to submerge any part of the handle as the cleaner will tarnish the finish. Add some Puly Caff and mix thoroughly to prevent the powder sinking to the bottom. Soak overnight and discard the liquid in the morning, rinsing and wiping out the portafilters before use.

Here’s a tip for new baristas. When replacing the coffee baskets in the portafilters, give them a smart slap with your palm. Pushing the baskets in slowly can pinch your hand – as I learned the hard way.

Barista cloth hygiene

Different types of cloth are suitable for different cleaning tasks. You will make your life easier if you use the best type of cloth for the job in hand. For health and safety reasons, always keep your cloths separate and start each day with a fresh set, replacing them when they get dirty.

One of your cloths should be a microfibre cloth used solely for wiping down the machine casing. Another cloth can be used for wiping up spillages.

Use a different cloth again for wiping down steam wands. While J cloths are a good choice for this, I prefer a black flannel as it is slightly coarser and doesn’t show the milk stains.

Cleaning and purging your steam wands

My final tip for this blog post focuses on keeping your steam wands clean, hygienic and effective.

If you send your machine to us or call us out to your Coffee machine for its annual service, we will thoroughly clean the steam wands but you can save yourself a lot of hassle by following this simple tip:

After using your steam wand, wipe it down instantly with a dedicated cloth (as I mentioned before, I prefer to use a black flannel). Then purge for two seconds. This will remove the milk residue from inside and outside the wand.

This may seem a chore but if you leave that milk residue there for just a minute, it will have welded itself to the wand. This leads to some of the horror scenes I’ll go through further down the page.

You should also purge your steam wands before you use them. Condensation can quickly build up on your wand as it cools and if you don’t purge, the excess water will bubble up and you won’t get the microfoam needed for decent latte art. In heavy water areas, you could even end up with some limescale build up.

Again, a two second purge is all you need to avoid these issues.

Important note:

If you or your staff are doing any of the following, you are definitely not wiping down your steam wands properly.

  1. Scratching old milk off with a knife or brillo pad. If you are spending 15 minutes scrubbing off congealed milk, you are not only wasting time, you are removing the finish from your steam wands.
  2. Soaking your steam wands in a jug overnight. Worse still, some staff leave the steam valve open while doing this. You might come in every morning and congratulate yourself when you see the brown muck that has come off the steam wand overnight. What you might not realise is that your depressurising espresso machine will have drawn a quarter of that contaminated water back into your boiler. So, the next time you draw some water from that boiler to make a cup of tea, you might notice a brown tinge and a subtle milky flavour!

If I see evidence of any of these practices in a coffee outlet, I will not drink from that machine. Nor would most baristas. If you have been contaminating your boiler over a long time with dirty water, you will need to book a service to get it cleaned as you won’t be able to access the boiler yourself.

Tailored training from Cartwright Coffee

Please note that this is only a basic guide to the essentials of keeping your espresso machine clean. Cartwright Coffee offers training which can include more specific cleaning tuition, based on your needs. For example, we can teach more experienced staff how to remove and replace the shower attachments under the group heads for a really thorough clean.

Please get in touch with us to find out more about our training packages, service plans and anything else we can help you with.