Bitter, or watery
Usually these are the same problem seen from two sides. Bitter often means you pulled too much out of the grounds. Watery often means you pulled too little. Neither is fixed by adding sugar.
Brewing is extraction: hot water dissolving substances out of coffee grounds. Extract too little and the cup is thin and sour. Extract too much and it turns harsh and bitter. There is a window in between.
What moves the needle
- Grind size. Finer grounds extract faster; coarser grounds extract slower.
- Water temperature. Hotter water extracts faster.
- Time. The longer water is in contact with coffee, the more it takes.
- Ratio. How much coffee to how much water.
Strong is not the same as over-extracted. Strong is a ratio. Bitter is a mistake.
Most people reach for more powder when a cup tastes weak. Sometimes that is right. But if the grind is too coarse for the method, more powder simply gives you more of the same thin cup. Change one thing at a time, and taste between changes.
Curious what this tastes like in the cup? See the coffees.