7 Common Espresso Mistakes (And How to Fix Them)

Home espresso is one of those hobbies that looks simple from the outside but has about a thousand little details that can make or break your shot. The good news is that most bad espresso comes down to a handful of very fixable mistakes. I've made every single one of these — some of them for embarrassingly long — and once I figured out the fixes, my shots went from mediocre to genuinely cafe-quality. So if your espresso tastes bitter, sour, watery, or just kind of off, chances are one of these seven mistakes is the culprit.

Mistake #1: Wrong Grind Size

This is the big one — the single most common reason home espresso tastes bad. Espresso needs a very fine grind, but not all fine grinds are equal. If your grind is too coarse, water rushes through the coffee puck in a few seconds, barely extracting anything. You end up with a pale, watery shot that tastes sour and thin. If your grind is too fine, the water can barely get through at all. Your shot takes forever to pull, and the result is dark, bitter, and astringent — like chewing on a coffee ground.

The target is a shot that takes about 25-30 seconds to pull roughly 36 grams of liquid from 18 grams of ground coffee. If your shot finishes in 15 seconds, go finer. If it takes 40+ seconds or barely drips out, go coarser. Make small adjustments — one notch at a time on your grinder — and pull a new shot after each change. It's a process, but once you find the sweet spot for a particular bag of beans, you'll only need tiny tweaks from there. For a deeper dive, check out our complete grind size guide.

Mistake #2: Inconsistent or Bad Tamping

Tamping is the step where you press the ground coffee into a flat, even puck inside the portafilter. If you tamp unevenly — pressing harder on one side than the other — you create channels where water takes the path of least resistance. That water rushes through the thin spot, over-extracting that section while under-extracting the rest. The result is a shot that's somehow both bitter and sour at the same time, which is incredibly frustrating when you can't figure out what's going wrong.

The fix is simpler than you think. You don't need to press with a specific force — the exact number of pounds doesn't matter nearly as much as being level and consistent. Place the portafilter on a flat surface or a tamping mat, hold the tamper like a doorknob (not like a hammer), and press straight down until the coffee stops compressing. Keep your wrist straight and your elbow above the portafilter. The goal is a flat, even surface every time. Some people find a calibrated tamper helpful — it clicks when you reach a set pressure — but honestly, just focusing on levelness will solve 90% of tamping-related issues.

Mistake #3: Using the Wrong Dose

Eyeballing your coffee dose is a habit that's surprisingly hard to break, but it'll hold your espresso back indefinitely. Even a gram or two of difference changes the extraction dramatically. Too much coffee and the puck is too dense, causing slow extraction and bitterness. Too little and there's extra headspace above the puck, water hits it unevenly, and you get channeling and sour, thin shots.

Get a small kitchen scale that reads to 0.1 grams — you can find decent ones for under $15. Weigh your dose every single time. For most double portafilter baskets, the sweet spot is between 17 and 19 grams, with 18g being the most common starting point. Check what your specific basket is rated for (it's usually stamped on the side or listed by the manufacturer) and stay within a gram of that number. Once you're weighing consistently, you remove one of the biggest variables from your espresso equation, and everything else gets easier to dial in.

Mistake #4: Using Stale Beans

Coffee is a fresh product, and espresso is especially unforgiving with stale beans. When coffee beans lose their freshness, the CO2 that drives crema production dissipates, the volatile aromatics fade, and the flavors go flat and cardboard-like. A shot pulled with beans that are three months past roast will taste dull and lifeless compared to the same beans at two weeks post-roast. It's genuinely night and day.

For espresso, beans are at their best between about 7 and 30 days after roasting. The first week they're still degassing aggressively, which can make shots taste a bit wild and inconsistent. After about a month, they start to noticeably decline. Buy from a local roaster if you can, and look for a roast date on the bag — not a "best by" date, which is meaningless. Buy only what you'll use in two to three weeks, and store your beans in an airtight container away from light, heat, and moisture. A simple mason jar works fine. Fancy vacuum canisters are nice but not necessary.

Mistake #5: Wrong Water Temperature

Water temperature is one of those variables that people tend to set once and forget about, but it has a huge impact on extraction. Most espresso machines work best between 90°C and 96°C (195°F to 205°F). Too hot and you over-extract the coffee, pulling out harsh, bitter, and ashy flavors. Too cold and you under-extract, producing a sour and thin shot that lacks sweetness and body.

If your machine has a PID controller (a digital temperature display), check that it's set in the 93-94°C (200-201°F) range as a starting point. For lighter roasts, you might push that up to 95-96°C to help extract those denser beans. For darker roasts, dropping to 90-92°C can help avoid the burnt, smoky flavors that dark roasts are prone to at higher temps. If your machine doesn't have a PID, the best you can do is a temperature surfing technique — flush some water, wait for the boiler to stabilize, and then pull your shot. Consistent temperature equals consistent shots.

Mistake #6: Not Preheating Your Equipment

This one's sneaky because it doesn't seem like it should matter that much, but it absolutely does. If your portafilter, group head, and cup are cold, they suck heat out of the water during extraction, dropping the effective brew temperature by several degrees. That means under-extraction, sour flavors, and a thinner body. I spent months wondering why my first shot of the morning always tasted worse than my second one before I realized the problem was temperature.

The fix is dead simple. Turn your machine on at least 15-20 minutes before you plan to brew. Lock the empty portafilter into the group head while the machine heats up — this gets both the group and the portafilter up to temperature together. Run a blank shot (just water, no coffee) right before you dose and tamp. And preheat your espresso cup with hot water or by placing it on the cup warmer on top of the machine. These steps take almost no extra time, but the improvement in consistency is dramatic. Your first shot of the day should taste just as good as every other one.

Mistake #7: Not Cleaning Your Machine

Old coffee oils are the silent destroyer of good espresso. Every time you pull a shot, a thin layer of oil gets deposited on the group head, the shower screen, and inside the portafilter basket. Over time, those oils go rancid — and rancid coffee oil tastes exactly like it sounds: stale, acrid, and unpleasantly bitter. If your espresso has a weird off-flavor that you can't seem to dial out no matter what you change, a dirty machine is probably the reason.

Daily, you should flush the group head with water after every session and wipe out the portafilter basket. Weekly, do a backflush cycle with a cleaning tablet or powder (like Cafiza) if your machine has a three-way solenoid valve. Monthly, soak your portafilter basket and shower screen in a cleaning solution for 15-20 minutes. And every few months, descale your machine's boiler according to the manufacturer's instructions. It sounds like a lot, but each step takes less than five minutes, and the difference in taste is impossible to ignore once you've experienced it.

Bringing It All Together

Here's the thing about espresso — it's a skill, and like any skill, it takes practice. But the learning curve flattens out faster than you'd expect once you fix the obvious mistakes. Start by getting your grind size and dose consistent, make sure your beans are fresh, and keep your machine clean. Those three things alone will transform your shots from mediocre to genuinely good. The rest — temperature, tamping, preheating — are the refinements that take you from good to great.

If you're still struggling with specific issues, our grind size guide goes deep on the relationship between grind and extraction. And if you're thinking about upgrading your setup, take a look at our best espresso machines for beginners roundup to find a machine that makes it easier to pull great shots consistently. You've got this.