Why does my pour over coffee taste bitter?

Bitterness in coffee is a sign that you have extracted beyond the 'sweet spot' of the bean. While some bitterness is expected in coffee, it should be a pleasant, dark-chocolate-like note rather than a harsh, drying, or burnt sensation. When you experience the latter, it means your brewing process has been too aggressive, pulling out the tannins and heavy compounds that are meant to stay in the grounds.

The most common culprit is grind size. If your grounds are too fine, they create more surface area for the water to act upon, which speeds up extraction significantly. Try adjusting your grinder to a coarser setting to slow down the extraction rate. Additionally, check your water temperature. If you are using boiling water (212°F/100°C) for a dark roast, you are likely scorching the coffee; try dropping your temperature to 195°F–200°F to see if the bitterness subsides.

Brew time is another critical factor. If your pour-over is taking significantly longer than the recommended 3 to 4 minutes, the water is spending too much time in contact with the coffee. This is often a result of 'fines'—tiny coffee particles—clogging the filter and slowing the flow. If you notice your bed of grounds looks muddy or silty at the end of the brew, your grinder might be producing too many fines, and you may need to adjust your technique or upgrade your equipment.

Finally, consider your water quality. If your water is too soft, it can actually lead to an over-extraction of acids and bitter compounds. Conversely, if your water is too hard, it can mask the sweetness of the coffee. Using filtered water with a balanced mineral content is one of the most overlooked ways to fix a bitter cup. Start by changing one variable at a time—grind size is usually the best place to start—to isolate the cause of the bitterness.