Five year old drip machine, hard-ish tap water through a jug filter, 60 g of coffee to a litre, medium grind on a burr grinder. It used to finish a full carafe in about six minutes and now it takes eleven, and the coffee that comes out tastes watery rather than bitter, which surprised me. Same beans and same dose as always. Is a slow brew making it weaker, and is this a descale job or a dead machine?
Slow brew on an old machine is scale nine times out of ten, and yes it makes the coffee weaker rather than stronger. The heating element scales up, the water never gets properly hot, and it dribbles out at a temperature that extracts the easy sour and sweet compounds and none of the body.
Descaled mine with citric acid solution, ran two clean water cycles after, and the brew time went from just over ten minutes back to six and a half. The water that came out of the first cycle had visible grit in it. If you are on hard water and have never descaled in five years, that is your answer before you buy anything.
Citric acid over vinegar, agreed. I used neat vinegar on a machine once because a video said to, and it ate a seal and left the thing smelling of chips for a month. Descaler or citric acid at the dilution on the packet, and run the rinse cycles.
Descaled last night. Nine minutes rather than eleven, so partway there. Doing a second round tonight.
Measure the water going in and the coffee coming out. If you put a litre in and get 780 ml out on a machine that used to give you 850, you have a leak or a blockage and you are also brewing at a different ratio than you think. That one measurement tells you more than any tasting note.
Descale first, obviously. But if you get to the far side of two descales and it is still slow, a five year old sub-100 drip machine does not owe you anything. I replaced mine with one of the certified brewers that has to hit a temperature and contact time band to get the badge, it was several times the price, and it is the only kitchen thing I have bought that made the coffee measurably better with no change in technique.
Going to push back on the descale-first crowd slightly. Thin and watery with a longer contact time is odd, because longer contact usually means more extraction, not less. That combination often means the water is channelling through one part of the bed and running around the rest, which is a shower head problem, not a scale problem. Take the top off, look at the spray pattern over a dry basket, and see whether it is one sad stream in the middle. If it is, that is a clog, and descaling may or may not clear it.
Watch out for the filter jug too. Softened or over-filtered water with almost nothing left in it extracts badly and tastes hollow, which reads as watery. If your jug filter cartridge is months overdue it is doing nothing, and if it is brand new and your tap water is very soft to start with you can end up under-extracting for a completely different reason.
@immersion_ivy · 6mo ago · 2 replies
Add a thermometer to the argument. Brewing temperature wants to be in the low to mid nineties Celsius and a scaled or simply cheap machine often sits ten degrees under that. I stuck a probe in the brew basket on a machine that was making exactly the thin cup you are describing and it peaked at 84 C, which is why it tasted like weak tea no matter what the dose was.
Your 60 g per litre is the standard ratio and is not the problem. If it still brews cold after descaling, the machine is the problem, and no grind adjustment will save it.
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@slowtrainjo · 6mo ago
Cheap probe thermometers in the basket read low because of evaporative cooling on the sensor, so take single readings with a pinch of salt. The direction is right though, most sub-100 machines never reach temperature, which is the whole point of the certification programmes.
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