Why Your Coffee Tastes Bitter: Common Brewing Mistakes
By Kiss the Hippo Coffee | London's Premier Specialty Coffee Roastery | Published: 2026-10-17
Category: Tips & Care
Discover the most common reasons for bitter coffee and learn how to fix over-extraction, water temperature, and grind size issues for a smoother cup.
Quick Answer
Bitter coffee is almost always a sign of over-extraction, where too much of the bean's bitter compounds dissolve into your cup. The fastest fix is to grind your coffee coarser, use slightly cooler water, or shorten your brew time.
Over-Extraction: The Main Cause of Bitterness
When hot water stays in contact with coffee grounds for too long, or the grind is too fine, it pulls out harsh, bitter flavours. This is called over-extraction. The ideal brew time varies by method: for a pour-over like the Hario V60, aim for 2.5 to 3 minutes total. If your coffee tastes dry and astringent, you're likely over-extracting.
A simple way to test this is to coarsen your grind just one step and keep everything else the same. If the bitterness fades, you've found the culprit. If the coffee becomes sour or weak, you may have gone too far — balance is key.
Water Temperature and Quality
Water that is too hot (above 205°F / 96°C) can scorch the coffee, producing burnt, bitter notes. Specialty coffee roasters like Kiss the Hippo recommend using water just off the boil, around 200°F (93°C), for most light to medium roasts. If you don't have a thermometer, let boiling water sit for 30-45 seconds before pouring.
Also, hard or mineral-heavy water can exaggerate bitterness. If your tap water tastes metallic, try filtered or bottled spring water. The difference is often dramatic.
Grind Size and Consistency
A fine grind increases surface area and extraction speed, but too fine leads to bitterness. For a Hario V60 pour-over, a medium-fine grind (like table salt) is a good starting point. If your coffee tastes bitter and the brew takes longer than 3.5 minutes, your grind is likely too fine.
Inconsistent grinds (both fine and coarse particles) also cause uneven extraction, with the fine bits over-extracting and adding bitterness. A quality burr grinder helps here, but even with a blade grinder, you can sift out the finest particles with a fine-mesh strainer.
Bitter Coffee Diagnosis
- Symptom: Coffee tastes harsh, dry, or astringent, often with a lingering bitter aftertaste. This is almost always over-extraction.
- Likely Cause: Grind too fine, water too hot, brew time too long, or a combination of these. Check your grind size first — it's the easiest variable to adjust.
- Corrective Action: Coarsen your grind by one setting, use water just off the boil (around 200°F), and reduce brew time by 15-30 seconds. Brew a test cup. If still bitter, repeat the adjustment. If sour, you've gone too far — go back one step.
- When to Stop & Choose Another Option: If after three adjustments the coffee is still bitter, the issue may be the coffee itself — some dark roasts or low-quality beans are naturally bitter. Try a different origin or roast level. Consider trying a well-balanced single origin like Colombia, La Providencia de Jeshua, which offers fruity and sweet notes that are forgiving of minor brew errors.
Products That Help You Brew Better
- Hario V60 02 Project Waterfall Filter Papers: The Hario V60 02 Filter Papers, Project Waterfall Edition combine quality brewing with meaningful impact. Designed for the Hario V60 02 Dripper, these premium filters ensure clean, balanced coffee while supporting Project Waterfall, a charity bringing clean water and sanitation to coffee-growing communities worldwide. Using high-quality filter papers reduces papery off-flavours and ensures a clean extraction, so you can better judge your brew ratio and avoid bitterness.
- Colombia, La Providencia de Jeshua: Producer Fabian Acevedo Farm/Mill La Providencia Cultivar Papayo Process Extended Washed Location La Argentina, Huila Altitude 1,750 MASL Harvest August 2025 Expect notes of Blackcurrant, Panela, Black Tea A well-processed, single-origin coffee like this one gives you clear flavour notes, making it easier to dial in your brew and spot over-extraction when the tea-like notes turn harsh.
