A pressurised — or dual-wall — basket has a second layer with a single small hole, which creates artificial back-pressure.
What it does
The coffee bed no longer needs to provide resistance. Pressure builds behind the small hole instead, and the liquid is forced through it, aerating on the way out.
The result looks like espresso, with thick foam on top.
Why it exists
So that machines can produce something espresso-like from pre-ground supermarket coffee and a poor grinder — neither of which can build proper resistance.
Almost every entry-level machine ships with one.
Why it is a compromise
The foam is not crema. It is aerated liquid, and it collapses quickly and tastes of nothing.
Grind, dose and tamp barely matter, because the basket, not the coffee, controls the resistance. Everything you would adjust is neutralised.
The extraction is genuinely worse — less even, less complete.
When to use it
If you have no grinder and are using pre-ground coffee, it is the correct choice. A non-pressurised basket with pre-ground gives a fast, sour, thin shot.
When to switch
The moment you have a burr grinder capable of espresso. Buy a standard single-wall basket for your portafilter size — they are inexpensive.
Expect the first shots to be bad. You now have to do the work the basket was doing.
The check
Look inside. A single small hole in a second layer is pressurised. Many fine holes is single-wall.
Last reviewed 8 August 2026