Cleaning is not maintenance in the cosmetic sense. Coffee oils oxidise and turn rancid, and scale physically blocks flow paths. A dirty machine produces bad coffee no matter what beans you buy, and a scaled machine dies early.
The schedule
| Frequency | Task | Time |
|---|---|---|
| After every shot | Flush the group, wipe the shower screen, knock and rinse the basket | 15 s |
| Daily | Water backflush, empty and rinse the drip tray, purge the steam wand | 2 min |
| Weekly | Detergent backflush, soak the portafilter and basket, clean the steam wand tip, brush the grinder | 15 min |
| Monthly | Grinder burr brush-out, soak the shower screen, check the group gasket | 30 min |
| Quarterly to yearly | Descale, replace the group gasket, replace the water filter | 1 h |
What backflushing removes
Every shot leaves coffee oils and fine particles on the shower screen and inside the three-way valve. Over days these oxidise into a sticky film that is bitter, rancid, and partly insoluble in water.
A water backflush pushes hot water backwards through the group and out the discharge, clearing loose grounds. A detergent backflush dissolves the oil film. Water alone cannot do this, which is why weekly detergent is the interval that matters.
Descaling: the decision that determines machine life
Scale is calcium carbonate, deposited when water with high hardness is heated. It forms on every hot surface: the boiler, the thermoblock, the group. A 1 mm layer of scale can reduce flow by 30 percent and causes temperature instability that no amount of technique fixes.
| Water hardness | Descale interval | Better option |
|---|---|---|
| Under 50 mg/L | 6 to 12 months | Nothing needed |
| 50 to 100 mg/L | 3 to 6 months | Softening filter |
| 100 to 175 mg/L | 2 to 3 months | Softening filter or dilution |
| Over 175 mg/L | Monthly | RO water, do not use tap |
The correct answer to hard water is not more descaling. Descaling is a chemical attack on the machine; doing it monthly for years shortens its life. Fix the water and descale rarely. This is the single most consequential maintenance decision you make.
How to descale without damaging anything
- Use citric acid or a purpose-made descaler. Never vinegar.
- Follow the machine's ratio, usually 1 to 2 tablespoons of citric acid per litre.
- Run half the solution through, let it sit 15 to 20 minutes, run the rest.
- Rinse with at least two full tanks of clean water.
- Pull and discard two shots before drinking.
Machines with aluminium boilers are sensitive to acid. Check the manual before descaling any machine with aluminium components: some manufacturers specify a specific product for exactly this reason.
The grinder is part of the machine
Rancid oils in a grinder are invisible and they ruin cups. Brush the burr chamber weekly, and every month or two run a small amount of grinder cleaning tablets through, then discard the output and grind a sacrificial dose. If your coffee tastes stale with fresh beans, the grinder is the first suspect.
Signs you are overdue
- Shots run slower than they used to on the same grind setting
- Temperature seems unstable between shots
- The shower screen has visible dark residue or blocked holes
- A metallic or cardboard taste that does not change with new beans
- Steam wand has hardened milk deposits on the tip
Any of these means clean now, not next month.