Explainer · Espresso machines · Grinders
Pressurised or non-pressurised baskets?
The small metal basket that holds the coffee decides whether your machine can use pre-ground coffee, and how much difference a good grinder will make. This guide explains the two kinds and when to switch from one to the other.
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The basket is the metal cup, with holes in its base, that holds the ground coffee. It clips into the portafilter, the handle you lock into the front of the machine. Few people think about it when they buy a machine, yet it changes how the machine behaves more than many of the specs on the box. When the pump pushes water through the coffee, something has to slow the water down, and the basket decides what that is.
There are two kinds. Most machines under £400 come with pressurised baskets, and some come with both. Traditional machines usually come with non-pressurised ones only. Knowing which is which stops you buying a grinder you don’t need yet, or a machine that can’t make use of the grinder you already own.
How a non-pressurised basket works
A non-pressurised basket, also called a standard or single-wall basket, has hundreds of small holes across its base. The holes let the water straight through, so all the resistance comes from the coffee itself. The pump has to push water through a tightly packed layer of very finely ground coffee, which baristas call the puck.
So the grind decides how the shot turns out. If it’s too coarse, the water runs through in about ten seconds and the shot tastes thin and sour. If it’s too fine, the coffee barely drips out. When the grind is right, the shot pours in an even stream, and the crema (the golden foam on top) comes from the coffee itself. The basket does nothing to help, so the result depends entirely on your coffee and your grinder.
How a pressurised basket works
A pressurised basket, sometimes called dual-wall, has two layers. The inner wall has holes like a normal basket. The outer wall has a single small hole. Water can only leave through that pinhole, so pressure builds up behind it whatever the coffee is doing.
This makes it very forgiving. Supermarket pre-ground coffee, slightly stale beans and coffee that hasn’t been pressed down (tamped) evenly all still give a drinkable shot with foam on top. The foam looks like crema, but much of it is air forced into the coffee as it squirts through the hole. The shot usually tastes flatter than a good one from a standard basket. You’ll notice that more in a straight espresso than in a latte.
A pressurised basket hides the difference between good and bad grinding. That helps when you’re starting out, and holds you back once you own a good grinder.
How to tell which you have
Turn the basket over. A non-pressurised basket has a base covered in holes. A pressurised one has a single hole in the middle, or a small plastic or rubber insert, and often looks like two baskets fitted together. If your machine came with both, they’re usually marked.
Which machines come with which
Pressurised only. Some compact machines are designed entirely around pre-ground coffee. They’re easy to use and forgiving, but a better grinder makes much less difference to them, and our quiz tells you so when it pairs a grinder with one.
De'Longhi Dedica Duo (EC890)
Metal
Heat-up time 40 seconds · Width 14.9cm
Smeg ECF02
Cream
Heat-up time 60 seconds · Width 14.9cm
Both kinds. For a first machine, these give you the most options. You can use the pressurised baskets with pre-ground coffee now and switch to the standard ones when you buy a grinder, without replacing the machine.
Sage Bambino
Brushed Stainless Steel
Heat-up time 3 seconds · Width 16cm
Gaggia Classic E24
Inox
Heat-up time about 5 minutes · Width 23cm
Sage Barista Express
Brushed Stainless Steel
Heat-up time 60 seconds · Width 33cm
Non-pressurised only. This covers most traditional and enthusiast machines. They need freshly ground coffee from a grinder made for espresso, so budget for one from the start.
Lelit Anna PID (PL41TEM)
Polished Stainless Steel
Heat-up time about 10 minutes · Width 23cm
Rancilio Silvia
Stainless steel
Heat-up time about 10 minutes · Width 23.5cm
Lelit Mara X (PL62X)
Brushed stainless steel
Heat-up time about 24 minutes · Width 22.5cm
These machines are examples, researched from manufacturer specifications and owner reports. We haven’t used them ourselves.
Can you use fresh beans in a pressurised basket?
Yes, and it will taste better than stale pre-ground coffee. Grind a little coarser than you would for a standard basket, though. Very fine coffee can block a pressurised basket, because the coffee and the pinhole are both holding the water back. Once you’ve bought a grinder, it usually makes sense to move to standard baskets anyway.
When to switch
Switch when you have a grinder that’s made for espresso and can make small adjustments. With one of those, a standard basket gives noticeably better shots, especially for straight espresso and lighter roasts. Without one, stay with the pressurised basket. A standard basket used with the wrong grind makes worse coffee than a pressurised one.
Expect the first few days to be messy. You’ll need to grind finer, weigh your coffee and tamp evenly, and your first shots will probably run too fast or too slow. That’s normal, and it doesn’t take long to get right.