What Are The Most Common Tamping Mistakes That Cause Channeling?

Are you doing everything right when tamping, but still getting wild channeling in your espresso shots?

It’s one of the most frustrating things for home baristas you’ve dialled in the grind, you’ve weighed your dose, your shot should be great… and yet it gushes out one side of the portafilter like a busted tap. Been there. And if you haven’t, you probably will.

The truth is, tamping mistakes are a huge cause of channeling, and most of the time, it’s got nothing to do with your tamper’s shape or how hard you’re pushing. It’s the little things. The habits. The overlooked steps that make or break your puck prep.

Let’s unpack the biggest tamping slip-ups that are causing channeling and what to do about them.

You're relying on tools without fixing your prep

Using a dedicated tamper has its benefits, especially a self-leveling one that flattens things out evenly.

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But here’s the thing even the best tamper won’t save a poorly prepped puck.

What I’ve seen is that home baristas often use a good tamper or a puck screen and assume everything will flow smoothly. But if your distribution is sloppy, or the grounds are clumped near the walls of the basket, you’ll still get channeling. Especially the kind that hugs the edge and blasts through one side.

That’s where distribution tools like wdt needles come into play used properly.

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If your WDT tool has extremely thin needles, or you're fluffing the grounds too aggressively, you can end up with a puck that's light and airy in the middle and compact around the edges. That’s a recipe for uneven extraction.

Here’s another article that walks through how bad WDT technique can ruin your shots.

Your tamp pressure isn’t the problem - your angle is

Everyone’s obsessed with how hard to tamp. 15kg? 30kg? Doesn’t matter.

What matters more is how even your tamp is. A slight tilt can send water flowing to one side, creating a path of least resistance.

This usually happens when tamping freehand without a stable tamping station especially if you're rushed or distracted. It's easy to press slightly off-centre.

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If you're using a force tamper or calibrated tamper, that's great but make sure your basket is level. Even a 1° angle matters.

You’re over-distributing and wrecking the puck structure

I’ve made this mistake too many times thinking more WDT equals better. What actually happened? My shots got worse.

Over-distributing can loosen up the puck so much that it collapses under pressure. Water finds a crack, and suddenly your shot looks like Niagara Falls on one side.

What helps? Using distribution tools properly. Stir gently and not too deep. Focus on evenness, not fluffiness.

Also, after WDT, settle the bed slightly before tamping. Don’t go straight from fluff to force.

Here’s another article that talks about WDT depth and why it matters more than most people think.

Your coffee dose is too high for your basket

One common issue I’ve noticed is cramming too much coffee into a small basket. On paper, it might fit. But once tamped, it’s flush with the top.

Add a puck screen and now it's pressing into the group head. That compression causes puck fracturing. It might even look like the tamp was good but inside, you've got cracks and weak spots.

That’s why precision baskets are worth looking into. They help control flow and resist channeling especially with lighter roasts or higher pressures.

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There’s also a good breakdown here on how overfilling leads to shot instability.

Your grind is right but your distribution isn't

Another trap? You’ve dialled in the perfect grind size and think the rest will fall into place.

But if the grounds are domed in the middle or sunken at the edges, your tamp won't be level no matter what tamper you’re using.

Use a dosing funnel to keep things tidy and tap the portafilter gently to level out the bed before tamping.

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Even a few stray grinds on the rim can lift one side of your tamper, causing you guessed it uneven pressure and channeling.

You’re forgetting that espresso is ridiculously sensitive

Honestly, espresso is one of the most unforgiving ways to make coffee. Tiny changes make a big impact.

So yes, tamping matters. But it’s not just the press it’s the setup. The little touches that turn chaos into consistency.

Use a bottomless portafilter to actually see what’s happening beneath the basket. If you’re getting sprays or jets, your puck isn’t happy.

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You can also reach out to us if you’re not sure which tools are compatible with your setup just visit our contact page and we’ll help you out.

So, what should you fix first?

If you're just starting out, don't try to overhaul everything. Start with better distribution and consistent tamping. Make sure your bed is flat, your pressure is straight, and your puck isn’t jammed up too high.

Then use your bottomless portafilter to test. Watch the shot. Adjust one thing at a time.

And if you’re curious about getting your kit sorted, we’ve got all the essentials from tampers to WDT tools, scales, baskets, and more.

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Still chasing better shots? You might want to check out our coffee blends made in collaboration with local Aussie roasters.

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Or if you’re building your station from scratch, take a look at our barista kits made to suit your machine.

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And if you're still stuck don’t worry. Channeling hits everyone at some point.

The key is learning where it starts. And fixing it one tamp at a time.

Written By Laurie Nance

I'm the founder of Brewedco Coffee™, passionate about coffee, coffee tools, and helping others better understand how to utilize them. With years of experience in the coffee industry, I love sharing insights on brewing techniques, choosing the right equipment, and the science behind making the perfect cup.