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A drip coffee maker that brews slower every month has scale narrowing its heater tube, and the cure is a descale, not patience. The confirmation test takes one brew: time a full tank of plain water, no grounds. Under ten minutes for a 12-cup tank is normal; fifteen or more means the water path is choking. Descale, retest, and the machine that took twenty-five minutes goes back to eight. Everything else on the slow-brew list is quick to rule out.
Rule-out order
| Suspect | Check | Verdict |
|---|---|---|
| Scale (the usual) | Water-only brew takes 15+ minutes | Descale: 50/50 vinegar or descaler, 30-min soak, 2 rinse tanks |
| Paper filter collapse | Basket floods, filter folded over | Seat the filter flat; right size for the basket |
| Grind too fine | Bed of mud in the basket after brewing | Medium grind; espresso grind dams a drip basket |
| Overfilled basket | Grounds above the max line | Level scoops; big batches need the ratio, not a mountain |
| Weak heater (age) | Slow even after descaling, lukewarm coffee | The element is fading; repair rarely beats replacement |
Why scale slows the brew specifically
Drip machines move water by boiling it through a one-way valve: pulses of steam push hot water up the tube to the shower head. Scale coats the tube, the pulses shrink, and each pulse lifts less water, so the same tank takes twice the passes. The machine also runs hotter internally to do it, which is why chronic scale kills heating elements young. The full procedure, with the Keurig and Cuisinart variants, is in how to clean a coffee maker.
The gurgle glossary
Healthy machines gurgle rhythmically and finish with a triumphant sputter. A slow machine that clicks and sighs between weak pulses is scaled. One that gurgles hard but delivers a trickle has a blocked shower head or collapsed filter: pop the spray head cover if your model allows and rinse the pinholes. Silence with a hot plate means the pump-valve side has failed, which on a budget drip machine is the end of the road, and the drip guide covers what replaces it honestly.
Keep it fast
Descale quarterly on hard water (monthly if the city report says very hard), use filtered water if the tap tastes of minerals, and run a water-only timing brew twice a year as the machine's physical. Slow brew is the earliest, cheapest warning drip machines give; the ones that die young are the ones nobody timed. Machines with their own quirks have their own guides: the general slow-brew page covers symptom depth, and this page's rule-out order gets most people home.
Related reading
FAQ
Why is my coffee maker suddenly so slow? Scale in the heater tube, almost always. Time a water-only brew: 15+ minutes for a full tank confirms it, and a descale fixes it.
How long should a drip coffee maker take? Roughly a minute per cup: a full 12-cup tank in 8 to 10 minutes. Double that means the water path is blocked.
Does vinegar really fix a slow coffee maker? Yes, for scale: 50/50 with water, brew half, soak 30 minutes, finish, then two rinse tanks. Citric descalers do the same with less aftertaste.
Improving your brew? Browse our free coffee tools, print the brew ratio card, and try our method: the descending pour.