Coffee tastes bitter or sour: what to change
Bitter and sour coffee point in opposite directions. Sour usually means the water pulled out too little from the grounds (under-extracted). Bitter and dry usually means it pulled out too much (over-extracted). Weak and strong depend on the ratio instead.
Change one thing per brew, then taste again. The table lists the changes in the order I would try them.
| Taste | Likely cause | Try, in this order |
|---|---|---|
| Sour, sharp, thin, salty | Under-extracted | Grind finer. Then brew a little longer. Then use hotter water, up to just off the boil. |
| Bitter, dry, astringent, hollow | Over-extracted | Grind coarser. Then shorten the brew time. Then lower the water temperature a few degrees. |
| Weak, watery, but not sour | Too little coffee for the water | Lower the ratio number by one (1:17 to 1:16). Keep the grind the same. |
| Strong and heavy, but not bitter | Too much coffee for the water | Raise the ratio number by one (1:15 to 1:16), or add hot water to the cup. |
| Bitter and sour in the same cup | Uneven extraction, often a mix of fine and coarse particles or channeling | Use a burr grinder if you have a blade one. Pour or stir more evenly. Do not change the ratio yet. |
| Flat, stale, cardboard | Old beans or pre-ground coffee | Check the roast date. Beans are usually at their best within a few weeks of roasting. Grind right before brewing. |
Why grind comes first
Grind size changes extraction more than the other settings do, and it changes it in a way that is easy to undo. A finer grind exposes more surface and slows the water down, so both sour and weak cups improve. A coarser grind does the reverse.
Ratio and extraction are tangled together. Using more water per gram of coffee also tends to extract more, so if you change the ratio, the taste can move in more than one way. That is why the table keeps ratio changes for cups that are only weak or only strong.
What a good result looks like by method
Each method has its own target time. If you are far outside it, fix that first: a V60 that drains in 1:30 is almost always too coarse, and a French press steeped for 10 minutes will taste bitter whatever the grind.
- French press: 4 minutes
- Hario V60 pour-over: 2:30–3:30 total
- AeroPress: 1:30–2:30
- Moka pot: 4–5 minutes on the stove
- Cold brew: 12–18 hours
- Espresso: 25–30 seconds
- Chemex: 4–5:30 total
- Kalita Wave: 3:00–3:30 total
- Automatic drip coffee maker: 5–8 minutes
- Turkish coffee: 2–4 minutes
- Japanese iced coffee: 2:30–3:30 brew, ready to drink right away
Espresso is the most sensitive to all of this. A shot that runs in under 20 seconds tends to taste sour and a shot over 35 seconds tends to taste bitter, so adjust the grind in small steps. See the espresso ratio page for dose and yield.
Two causes that are easy to miss
- Water. Very soft or very hard water, or water that tastes of chlorine, changes the cup. If the coffee tastes off in every method, try filtered water.
- A dirty brewer or grinder. Old coffee oils taste rancid and bitter. Rinse the brewer after each use and clean the grinder every few weeks.
Once the taste is right, write down the numbers. The calculator gives a link you can copy and keep for that recipe.