Cleaning and maintenance
Descaler
An acidic solution that dissolves mineral scale from inside boilers, elements and water paths. Different from a cleaner in every respect.
- Type
- Cleaning
- What it is for
- Cleaning and maintenance
- Who needs one
- Essential
- Consumable or kept
- Used up and replaced
- Materials
- Citric acid, Lactic acid, Sulphamic acid
- Needs attention
- By water hardness and the manufacturer's stated interval. Hard water may need it every month or two; soft water far less often.
Safety
Descalers are acids. Follow the product's instructions and the machine manufacturer's instructions exactly, never mix descaler with a cleaning detergent or any other product, protect skin and eyes, and never descale a machine whose manufacturer says not to. Where a manual specifies a proprietary descaler, use it.
What it is
Scale is calcium and magnesium carbonate deposited out of hard water by heat. It builds up inside boilers and on elements, insulating them, restricting flow, and eventually blocking valves. It cannot be brushed off from outside and it is not touched by detergent. A descaler is an acid — commonly citric, lactic or sulphamic — that converts it into something soluble.
How it works
Acid reacts with the carbonate deposit, releasing carbon dioxide and leaving soluble salts that rinse away. That is why a descaling machine fizzes.
Why people use one
Because scale is the most common cause of expensive failure in kettles and espresso machines, and because most manufacturers make descaling a condition of warranty.
What this actually changes
Separated by what it affects, because “improves your coffee” is not something you can act on. Where the evidence is thin or contested, it says so.
Equipment life
Real differenceDescaling on schedule is the difference between a boiler that lasts years and one that does not.
Taste
Modest differenceReasoned, not measuredA heavily scaled machine brews cooler and more slowly, which shows in the cup. Removing scale restores what the machine was doing before.
Safety
Modest differenceReasoned, not measuredScale on a heating element causes local overheating and can lead to failure.
Who it is for
Worth having if
- Anyone with a kettle or espresso machine on anything other than very soft water
Probably skip it if
- Anyone whose machine's manufacturer explicitly forbids descaling — some machines with particular boiler materials are supplied on that basis and require filtered water instead. Read the manual, not the internet
Using it well
- Use only a descaler the machine's manufacturer permits, at the concentration they state
- Run the full rinse cycle afterwards, then run a further tank through before making coffee
- Set the interval by your water hardness and the manufacturer's guidance, not by whether you can see anything
Common mistakes
Using vinegar
Effective on scale, damaging to some seals and gaskets, and the smell persists for a long time.
Instead: Use a product made for the machine unless the manufacturer names vinegar as acceptable.
Descaling instead of cleaning
Coffee oils remain and the machine still tastes stale.
Instead: They are two separate jobs on two separate schedules.
Skipping the rinse
The next several drinks taste sour and chemical.
Instead: Rinse more than the minimum, particularly with a strong descaler.
Cleaning and care
Store sealed and away from children. Do not decant into unlabelled bottles.
What you could use instead
Preventing scale with treated water
Slows scale formation; does not remove what is already there.
How to use it
Step-by-step techniques this equipment is part of.
When it goes wrong
Often used alongside
Other equipment this one is used with, or that the same brewing methods call for.
Drinks it appears in
Drinks that name this equipment, or that are brewed by a method requiring it.
Compare the options
Side-by-side comparisons this category appears in.