Cleaning and maintenance
Descaling a machine
Descaling removes minerals from inside. Cleaning removes coffee from the group. Doing one instead of the other leaves the problem untouched.
- Skill level
- Intermediate
- How long it takes
- Thirty to sixty minutes including rinsing
- Equipment needed
- Descaler
- Steps
- 6
Safety
Descalers are acids and machines contain near-boiling water under pressure. Follow the product's safety information and the machine's instructions, never mix chemicals, and never open or dismantle a pressurised component. Where the manual points to a technician, use one.
Your equipment’s instructions come first
Descaling intervals, permitted products and whether descaling is allowed at all are set by the machine's manufacturer. Their instructions override any general guidance here.
Why it works this way
Scale forms when hard water is heated, and it accumulates where the machine gets hottest — the element and the boiler. It insulates, so the machine brews cooler; it restricts, so flow drops; and it eventually blocks valves. None of that is visible from outside, which is why makers who permit descaling tie it to a prompt, a hardness setting or a schedule in the manual rather than to appearance. The one rule that overrides everything here: some manufacturers advise against descaling their machines and ask for filtered water instead, and their instructions govern.
What you need
Required
Helpful, not essential
How to do it
Read the machine's own descaling instructions first.
Some machines have a built-in cycle, some require a specific product, and some makers advise owners against descaling certain machines themselves.
Test your water hardness or check your supplier's figure to set the interval.
Harder water scales faster and softer water far more slowly, so the interval depends on your water and how much you use the machine. A fixed interval from the internet fits nobody.
Mix the descaler at the stated concentration and run it through as directed.
Stronger is not better. One maker of home machines gives the corrosion of metals by aggressive descalers as its reason for not recommending owner descaling at all.
Run the solution through every water path, including the steam wand and hot-water tap.
Scale forms wherever heated water goes, not only in the brew path.
Rinse with at least the volume of fresh water the instructions specify, then one tank more.
Residual acid tastes sour and unpleasant and is worth over-rinsing to avoid.
Discard the first drinks made afterwards.
A precaution, not a superstition.
How to tell it worked
Flow and heat-up time back to what they were when the machine was new, and coffee without the flat, cool character a scaled machine produces.
If it did not work
What you saw, what to change, and why the change works.
Coffee tastes sour and chemical after descaling
Change: Rinse several more tanks through.
Residual descaler is the usual explanation, and the only fix is more water.
Flow does not improve
Change: Consider a second cycle, then consult the manufacturer or a technician.
Heavy scale sometimes needs more than one pass, and a blocked valve is not a home repair.
Common mistakes
Descaling a machine the manufacturer says not to descale
Possible damage, and possible loss of warranty cover.
Instead: Read the manual. Where the maker advises against it, softer or filtered water and a service technician are the alternatives.
Using vinegar as a general substitute
Makers disagree: one manual read for this page excludes vinegar and another specifies it. Used on a machine whose maker excludes it, it risks damage.
Instead: Use only what your machine's maker permits.
Mixing descaler with cleaning detergent
An acid and an alkali react, and the result cleans nothing.
Instead: Never mix products. One job at a time.
Diagnose a specific problem
The science behind it
- Water hardness
How much dissolved mineral content your brewing water has.
- Alkalinity (buffering capacity)
Water's ability to resist a change in pH — a different property from hardness.
Drinks this makes
Brewing methods it applies to
Tools that help
Background reading
Learn next
Where this is taught
Become a Barista · Level 8
Cleaning and descaling are different jobs, and your manual outranks every schedule.
Become a Coffee Expert · Level 9
Hardness, alkalinity and what the minerals in your water do to extraction and taste.