Pressurised vs non-pressurised baskets
The cheapest part of an espresso machine, and the one that decides whether a better grinder will do you any good at all.
A pressurised basket has a restricting valve that creates back-pressure artificially, so it produces crema and a drinkable shot from an imperfect grind. A non-pressurised basket relies on the coffee bed itself to provide that resistance, which is what makes grind quality visible. Beginner machines ship with both; the pressurised one is a stopgap.
Published 2026-08-30 · Last reviewed 2026-08-30
Inside your portafilter is a metal basket with holes in the bottom. There are two kinds, and machines aimed at beginners usually ship with both.
What a pressurised basket does
A pressurised basket — sometimes called dual-wall — has a second wall with a single small hole, or a valve. Coffee sits in the top chamber; the restriction is in the bottom one. Water passes through the coffee, then through the restriction, which is what generates the pressure.
The consequence is that the coffee bed no longer has to provide the resistance. Grind is too coarse? The valve compensates. Uneven tamp? The valve compensates. You get a dark, crema-topped drink that looks like espresso.
That crema is mostly the result of the valve aerating the liquid on its way out, rather than of dissolved CO2 from fresh coffee. It looks the part. It behaves differently — it tends to dissipate quickly and it does not carry the same aromatics.
What a non-pressurised basket does
A non-pressurised, or single-wall, basket is just a basket with many small holes. All the resistance comes from the coffee itself. That means the grind must be fine enough and even enough to build about nine bars of pressure across the bed, and the puck must be level so water does not find a shortcut.
This is harder. It is also the only configuration in which better coffee, a better grinder or better technique change anything.
Why this decides your grinder budget
Here is the connection that makes this a budget question rather than a parts question. With a pressurised basket, a better grinder buys you very little — the valve is doing the work either way. With a non-pressurised basket, the grinder is the limiting factor in almost every home setup.
So the sequence is: you move to non-pressurised baskets, and immediately you need a grinder that can hit the espresso range with enough resolution to dial in. Which is exactly the argument in how much of your budget belongs to the grinder.
What ships with what
Most Breville machines supply both single- and dual-wall baskets, which is why they work on day one and improve later. De'Longhi's Stilosa supplies pressurised baskets only, and that is the main reason its upgrade path is limited. The Profitec GO ships with a bottomless portafilter and non-pressurised baskets — no training wheels, by design.
When to switch
When you own a grinder that can grind fine enough, with small enough steps to adjust. Not before. Switching first and then blaming the machine is the most common way people conclude that home espresso is not for them.
Questions people actually ask
Why did my espresso get worse when I switched baskets?
Because the non-pressurised basket stopped hiding your grind. That is what it is for. Grind finer until the shot slows down, and expect to adjust in small steps.
Can I use pre-ground coffee in a non-pressurised basket?
Rarely well. Supermarket pre-ground is almost always too coarse for espresso, and it cannot be made finer.