The puck is wet and soupy after the shot
Knocking out the portafilter reveals a sludgy, waterlogged puck rather than a firm one that releases cleanly.
Applies to: Espresso machine, Espresso
What a wet puck does and does not mean
CoffeeHQ explanation
People read the spent puck as a verdict on the shot. It is mostly a description of the machine. On a machine with a three-way valve, the valve opens when the pump stops and vents the water and pressure sitting above the puck into the drip tray, leaving a firm, fairly dry cake. A machine without that valve has nowhere to send that water. It stays on top of the coffee, and the puck comes out sloppy however good the shot was.
So the first question is which kind of machine you have. Many entry-level machines, most lever machines and all manual brewers leave a wet puck by design. On those, a pool of water on the coffee is the expected result of a correct shot.
Causes, most likely first
There are 3 likely causes, listed with the most probable first. Work down the list and change one thing at a time, so that when the problem goes away you know which change fixed it.
Cause 1 of 3 · Commonly the cause
Normal behaviour on a machine with no three-way valve
- How to check
- Did the espresso itself taste as expected?
- What to change
- Many machines leave water above the puck by design. A wet puck alone is not a fault if the shot tasted right.
Cause 2 of 3 · Reported, not independently verified
Dose too low for the basket, leaving space for water to sit
- What to change
- Increase the dose within the basket's stated range.
Cause 3 of 3 · Reported, not independently verified
Shot stopped early, leaving the group full
- What to change
- Allow the machine to complete its cycle before unlocking.
If none of these fixes it
Check the cleaning and descaling guide. Equipment that needs maintenance can cause several of these symptoms at once, and no change of recipe will correct it.
Work through it for your setup
The causes above are general. These go to the part of a diagnostic that takes this symptom one check and one change at a time.
- Make my coffee better: Espresso machineEvery reading for this brewer: the check, and the one thing to change first
- Espresso puck preparation: the sequence
Taste the shot before you judge the puck
If the espresso tastes balanced and ran in a sensible time, a wet puck needs no action at all. Wait ten seconds after the shot before unlocking, so that pressure can fall and some of the water can drain through, and knock the puck out over the bin.
A wet puck matters only when it arrives with a fast, thin, sour shot. Then it is one more sign of too little coffee in the basket: water has room to stand above a shallow bed. Add a gram and pull the same yield.
Easily confused with
- An under-dosed basket — Under-dosing gives a wet puck and a fast, weak shot together. A wet puck with a good shot is the machine, not the dose.
- A puck with holes in it — Pinholes or a crater in the surface are evidence of channelling. Wetness alone is not.
What not to change at the same time
Do not change dose and grind together to dry the puck out. You would be re-dialling a shot that may have been fine, to fix something that was never broken.
How to tell it is fixed
On a machine with a three-way valve, the puck knocks out as a firm disc. On a machine without one, there is nothing to fix: the test is the cup.
If that changed nothing
If a machine that does have a three-way valve has started leaving wet pucks, the valve may be blocked with coffee residue. That is a cleaning job, covered under backflushing in your manual.