Why Does My Espresso Taste Sour? (And How to Fix It at Home)

Sour espresso almost always means the shot is under extracted. The water ran through the coffee too fast to pull out the sweetness, so you're left with the sharp, acidic flavours that dissolve first. The fix is usually to grind finer so the shot runs slower. If that doesn't do it, check your ratio, your water temperature and how old your beans are.

Sour or bitter? How to tell

Sour tastes sharp and thin. It hits the sides of your tongue, can taste a little salty, and the finish disappears quickly. Bitter is harsh and dry, and it hangs around at the back of your mouth after you swallow.

Sour means under extracted. Bitter usually means over extracted. They need opposite fixes, so it's worth getting this right first. If yours is bitter, start with our guide to why espresso tastes bitter.

Sour also isn't the same as bright. A good coffee can have fruity acidity, like citrus or berries, that tastes clean and sweet. Sour is when that acidity is sharp and nothing balances it out.

How to fix sour espresso

Grind finer. This is the most common cause. If your shot runs out in under 25 seconds, the grind is too coarse. Go a step or two finer and pull another shot. Change one thing at a time so you know what actually worked.

Pull a longer shot. If the time is right but it's still sour, let more water through. Aim for roughly double the weight of coffee in the cup, so 18 grams of ground coffee gives you about 36 grams of espresso. Stopping at 25 grams will taste sour almost every time.

Check your temperature. Water that isn't hot enough under extracts. Give your machine time to warm up properly, run a little water through the group head with the portafilter attached to heat it, and warm your cup.

Check your roast date. Beans roasted a day or two ago are still releasing gas, which makes shots run unevenly and taste sour. Most espresso tastes best from about a week after roasting. At the other end, stale beans taste flat and sour too. Either way, the roast date on the bag tells you where you stand.

One more thing. Lighter roasts are harder to extract on a home machine. If you can't shift the sourness no matter what you change, a medium roast blend is far more forgiving.

Frequently asked questions

Why is my espresso still sour when I'm grinding fine?

Check your dose and your tamp. Too little coffee in the basket lets water rush through. An uneven tamp lets water find a gap and skip most of the coffee, which also tastes sour. Level the grounds before you tamp and press straight down.

Can milk cover up sour espresso?

It softens it a little, but you'll still taste it in a flat white or latte. Fixing the shot is quicker than hiding it.

How long should an espresso shot take?

Around 25 to 30 seconds from when you press the button. Faster usually tastes sour, slower usually tastes bitter.

Which beans are least likely to taste sour?

Medium and medium dark roast blends. They're sweeter, more forgiving to dial in, and taste good in milk. Our guide to the best beans for home espresso machines goes into more detail.

If you want something easy to dial in, Liberty is our house blend, a medium roast with chocolate and caramel sweetness. If you mostly drink milk coffee, Rhythm is a little darker and rounder. Both have the roast date printed on the bag.