When Your Pour-Over Goes Wrong, Diagnose Before You Dose
Every home brewer has had that moment. You nail the ratio, the water is fresh, the grinder is dialed, and yet the cup tastes sour, bitter, or takes forever to draw down. The good news is that pour-over mistakes almost always leave fingerprints in the cup, and once you learn to read them, fixing the brew becomes a short loop instead of an endless guessing game.
This checklist walks through the three most common complaints, sour, bitter, and slow drawdown, and maps each symptom to likely causes across the three dominant dripper families: conical (Hario V60, Origami, April), flat-bottom (Kalita Wave, April in flat mode), and bonded-paper (Chemex).
Sourness: Usually an Under-Extraction Problem
Sourness in pour-over is rarely about the coffee itself being bad. In most cases, your brew is simply stopping before the sweeter mid-range compounds have fully dissolved. Think of extraction like a staircase: acids come out first, sugars next, and bitters last. If you quit climbing at the second step, the cup leans sharp and thin.
A few common culprits:
- Grind too coarse. Water moves through large particles quickly and pulls out mostly surface acidity. If your 15g dose draws down in under two minutes on a V60, tighten the grind a few notches.
- Water too cool. Below roughly 90°C, solubility of sweeter compounds drops sharply. Light roasts especially want near-boiling water.
- Agitation too low. A gentle bloom and flat pours without any stirring can leave dry pockets in the bed. Hoffmann's Rao spin at the end of the bloom is a useful corrective.
- Short contact time. Brews finishing in under 2:30 on a V60 or 3:00 on a Chemex often taste underdeveloped, assuming a typical 15 to 20 gram dose.
Actionable tip #1: Before changing anything else, tighten grind by two or three clicks and repeat the exact same recipe. Grind is the single biggest lever on extraction, and isolating it lets you see its effect cleanly.
Scott Rao's advice here is worth internalizing: if the cup is sour, assume under-extraction first and adjust grind before temperature. Temperature is a smaller, finer lever.
Bitterness: Usually Over-Extraction, Sometimes Channeling
Bitter coffee is the mirror image problem. You have climbed past the sweet spot on the staircase and pulled out too many of the heavier, drier compounds. But bitterness can also come from uneven extraction, where part of the bed is over-extracted while another part is under-extracted. The cup tastes simultaneously hollow and harsh.
Signs and fixes:
- Grind too fine. Restriction increases, total brew time stretches, and extraction yield climbs past the pleasant window. Coarsen a few clicks.
- Water too hot, or dose too small. A 10g dose in a V60 with boiling water behaves very differently than a 20g dose. Smaller beds extract faster.
- Excessive agitation late in the brew. Aggressive pours after the halfway point can strip the bed unevenly.
- Stale or over-roasted beans. Deep roasts expose more soluble material, and stale beans release it unevenly. No brewing technique fully rescues either.
The Kalita Wave's flat bottom and three-hole plate tends to forgive grind errors better than a V60, but it can still over-extract if you pour too slowly. The Chemex, with its thicker filter and longer contact time, is especially sensitive to grind. On Chemex, go one notch coarser than your V60 baseline and you will usually be in the right neighborhood.
Slow Drawdown: A Geometry and Grind Conversation
A brew that stalls past 4:00 on a V60 or 5:00 on a Chemex is almost always telling you about either grind size or pour technique. The bed has compacted, fines have migrated to the bottom, and water can no longer pass through efficiently. This creates what extraction nerds call the espresso problem in a paper cone, where late water extracts way too much from the compressed bottom layer.
Diagnostic questions:
- Did you pulse-pour too aggressively? Heavy center pours punch a crater and drive fines downward. Use concentric circles and gentler wrist action.
- Is your grinder producing too many fines? Older blade grinders and entry-level burr grinders both produce a bimodal distribution. If drawdown always stalls regardless of setting, the grinder may be the bottleneck.
- Are you rinsing the paper filter? Especially on Chemex and thicker Hario tabbed filters, unrinsed paper can slow flow and add papery notes.
[Tetsu Kasuya](https://cup-timer.com/en/barista/tetsu-kasuya)'s 4:6 method, with its explicit pour schedule, often solves drawdown problems by preventing runaway agitation in the first place. The April Plastic and Origami dripper, both with wide outlets, also tend to avoid stalls when paired with appropriate paper.
Actionable tip #2: Keep a simple log. Record dose, grind setting, water temperature, total time, and one tasting note per brew. Three brews in, you will start seeing patterns that no single session reveals.
Closing the Loop With TDS and the Senses
If you own a refractometer, reading TDS and calculating EBF (extraction by fraction, or extraction yield) removes a lot of ambiguity. As a common rule of thumb, most specialty brews target an extraction yield in the 19 to 22 percent range, with TDS somewhere around 1.30 to 1.45 percent, though your roaster or the bean's origin can shift that window meaningfully. Without a refractometer, your palate is still a perfectly valid instrument. Sour means extract more. Bitter means extract less. Slow drawdown means check your grinder and your pours before blaming the dripper.
Pour-over rewards patience with diagnostics, not brute-force tinkering. Change one variable at a time, taste with intention, and the cup will tell you where it wants to go.