A not so distant relative of the sour cup of coffee is the bitter cup of coffee.  This is one of those times when someone says ‘it goes without saying…’ then proceeds to say it anyways?  Here we go, ‘it goes without saying that none of us want a bitter cup or a sour cup’ of coffee.  There, said.  So while neither the sour cup or the bitter cup are uncommon problems, both have some simple fixes! 

1. Over-Extraction

The #1 cause of bitter coffee is over-extraction.

When hot water stays in contact with coffee grounds for too long, it pulls out compounds past the point of balance.

Signs of over-extraction:

• Harsh, dry bitterness on the tongue
• Hollow or astringent aftertaste
• Coffee feels “thin” but still unpleasant

Common causes:

• Grind too fine
• Brew time too long
• Wrong coffee-to-water ratio (too much coffee)

Fixes:

• Use a coarser grind
• Shorten brew time (French press = 4 min, pour-over = 2.5–4 min, espresso = 25–30 sec)
• Stick to a balanced ratio (1:15–1:17 coffee to water by weight)

 

2. Water Temperature Too High

Brewing water that’s too hot extracts bitter compounds quickly. Boiling water (212°F / 100°C) is too aggressive for coffee.

Fix:

• Keep brewing water between 195–205°F (90–96°C)
• If you don’t have a thermometer, let boiling water sit for 30 seconds before pouring

 

3. Grind Size Problems

Grind size directly impacts extraction:

• Too fine: Over-extraction → bitter coffee
• Too coarse: Under-extraction → sour coffee

Fix:

• Match grind size to your brew method:
• Espresso → fine (similar to sand)
• Pour-over/drip → medium (similar to table salt)
• French press/cold brew → coarse (like sea salt)
• If your coffee tastes bitter, go one step coarser.  Note – this is a starting point, how much you are brewing at one time also influences the role of grind size.

 

4. Too Much Coffee (Ratio Imbalance)

Using too many grounds compared to water makes a brew that’s overly strong and often bitter.

Fix:

• Weigh your coffee and water with a digital scale
• Start with a 1:16 ratio (example: 30g coffee to 480g water)
• Adjust slightly to taste

 

5. Dirty Equipment

Coffee oils build up in brewers and turn rancid over time. This adds an unwanted bitter, burnt taste.

Fix:

• Wash your French press, drip machine, and grinders regularly
• Use coffee-specific cleaning tablets for espresso machines

 

6. Stale or Low-Quality Beans

Stale beans lose their sweetness and highlight harsher flavors, while low-grade coffee often contains defects that taste bitter or ashy.

Fix:

• Buy freshly roasted, high-quality beans

 

8. Poor Water Quality

Water that’s too hard or contains off-flavors can accentuate bitterness. Since coffee is 98% water, this matters a lot.

Fix:

• Use filtered water
• Avoid using distilled water as this gives a flat, boring taste due to the lack of minerals.
• Likewise, tap water with the added chlorine isn’t optimal either. 

Happy brewing!  May your coffee be awesome & your day amazing!  Truly a good day to have a good day!