August 22, 2025 Nicolas Di Stefano

How To Fix Under Extracted Coffee

Key Takeaways:

Why Under Extraction Happens: A course grind, short brew time, low water temperature, or an incorrect coffee-to-water ratio, prevent flavours from properly dissolving.
How Under Extracted Coffee Tastes: A sharp sourness, thin/watery body, lack of sweetness, and sometimes salty or vegetal notes, leaving a quick, hollow finish.
Simple Steps to Fix It: Try using a finer grind, increasing water temperature (to
90.5°C+), extending brew time, or adjusting your coffee-to-water ratio (aim for 1:15).

Have you ever been so excited to sip your morning coffee only to discover that it lacks flavour and tastes salty and sour? This is because you may have under-extracted your coffee, which is a very simple mistake to make.

The good news is that it is possible to steer clear of disappointing coffee. The days of under-extracted and over-extracted coffee can finally be put behind you. Here are a few solutions on how to fix under extracted coffee.

What Does Under Extracted Coffee Mean?

Before discussing how to fix under-extracted coffee, it is critical to understand what it means. When you brew a cup of coffee, hot water draws out the acids, sugars, solids, oils, and bitter flavours. If your coffee was extracted perfectly, you’ll end up with a delicious cup of coffee joe. However, if you didn't properly brew your coffee, it might taste thin, sour, and bitter.

What Does Under Extracted Coffee Taste Like?

Under-extracted coffee often has a distinct flavour that’s characterised by:

Sharp Sourness: An overpowering, unpleasant tartness.
Salty or Savory Notes: A subtle, alkaline, and salty mouthfeel.
Lack of Sweetness: The cup tastes thin or empty because sugars haven't developed.
Thin or Watery Body: A light, watery mouthfeel lacking richness or complexity.
Quick, Hollow Finish: Flavours fade rapidly, with little to no pleasant aftertaste.
Pale Crema: Espresso shots appear lighter with a thin, quickly dissipating crema.
Vegetal, Nutty, or Grassy Flavors: Undesirable green or raw notes.

Why is My Coffee Under Extracted?

Knowing what causes under extracted coffee is key to improving your flavours and aromas. Common causes include:

Too coarse a grind: Water passes through too quickly, preventing proper flavour extraction.
Too short a brew time: Not enough time for water to dissolve the full range of compounds.
Water temperature too low: Cooler water extracts less effectively from the grounds.
Insufficient agitation or contact: Grounds aren't fully saturated, leading to incomplete extraction.
Incorrect coffee-to-water ratio: Too much water or too little coffee can dilute the extraction.

How To Fix Under-Extracted Coffee?

The good news is that a few simple tweaks to your brewing method can transform under extracted coffee into a beautiful, well-rounded result. Try these four top tips.

1. Try a Finer Grind

Your coffee may not be extracting much flavour because the grounds are too coarse and the water is simply slipping through the spaces. You will extract more flavour from your coffee beans if you use finer coffee grounds. If your coffee tastes overly bitter, it's too fine. If it tastes acidic, it is too coarse.

2. Increase Water Temperature

If the water isn't hot enough, the desirable flavours won't be extracted properly. Use warm water, but not too hot, as this will cause the flavour to extract too quickly. In order to effectively extract the coffee's oils and flavours, we recommend brewing your coffee with water that is at least 90 degrees celcius.

3. Brew Longer

If the water passes through the coffee too quickly, you'll end up with a flavourless cup of coffee because there wasn't enough time to extract all the yummy flavours. Try brewing for a longer period of time to allow the flavours in the water to fully extract. However, avoid brewing for an excessively long period of time because this will result in over-extracted coffee and a bitter taste.

4. Fix Your Coffee-to-Water Ratio

You might be asking yourself how to fix under-extracted your coffee if the grounds were packed too closely together in one spot. The ideal coffee brewing ratio is 1 gram of coffee to 15 grams of water. If you don't use enough water, the flavours won't have time to develop.

Although you may discover that you prefer more or less coffee or water, this is usually the benchmark that most people adhere to. You may occasionally experience under-extracted coffee, but don't worry. As long as you remember these important indicators and common brewing mistakes, you can brew a delicious cup of coffee and avoid needing to find out how to fix under-extracted coffee.

Additional Reading

We're not done! Read some of our other content in our coffee Brewing blog, by following the links below.

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About the Author

Nicolas Di Stefano is a third-generation Master Roaster and Director of Primo Caffe. With decades of family tradition behind him, Nicolas combines time-honoured Italian roasting techniques with a passion for quality, delivering delicious coffee that Australians expect.