Is Water Accumulation in Espresso Portafilter After Extraction Related to Portafilter and Distribution Plate? How to Adjust Extraction Parameters?

For those with espresso machines, have you encountered this situation: after brewing, when you remove the portafilter, you find that the entire coffee puck is soaked, with a large amount of water accumulation on the surface, and the knocked-out puck is in a shapeless, muddy state.

Under normal circumstances, the extracted coffee puck should be relatively dry, and the knocked-out puck should be a relatively complete, solid cake. If you see the wet, soft state mentioned above, or water accumulation, that's not a normal phenomenon. Today, FrontStreet Coffee will discuss in detail what factors might cause this water accumulation problem.

Coffee Grounds Too Fine

Espresso extraction uses hot water under high pressure. When the grind is too fine, the gaps between coffee particles in the portafilter basket are significantly reduced. Even if the coffee machine reaches its maximum pressure value, hot water struggles to pass through these gaps to extract flavor compounds. At the end of extraction, some water may not pass through the coffee layer in time, accumulating in the puck and resulting in a wet, muddy state, or even water accumulation.

The most obvious phenomenon of extraction with too fine a grind is: the pressure gauge has reached peak pressure for several seconds, but the coffee liquid is still in a slow-drip extraction state, and the extraction time becomes relatively longer.

If water accumulation occurs due to too fine a grind, it's easy to identify and solve. Simply adjusting the coffee grind to be coarser can resolve this phenomenon.

Stale Coffee Beans

When beans are not fresh, it's difficult to determine the exact cause of water accumulation in the portafilter. This situation typically occurs among home espresso enthusiasts with low output consumption. With a daily consumption of one or two shots, a bag of espresso beans might last for a month, during which time almost all carbon dioxide in the beans has dissipated.

It's important to know that, like pour-over coffee, espresso machines also perform blooming on the coffee grounds during extraction, which is pre-infusion. When coffee grounds contain carbon dioxide, they expand under the effect of hot water and fill the gaps between particles. If there's little carbon dioxide left in the beans, they won't expand, and under the same grind setting, the flow rate of coffee liquid will become faster.

Typically, espresso extracted this way has little or no crema, is watery, and frequently experiences portafilter water accumulation problems. If possible, it's recommended to choose fresh coffee beans.

Too Much or Too Little Coffee

Typically, the portafilter baskets we use have a standard capacity for coffee grounds, and different models of baskets can accommodate different amounts of coffee.

If you simply want a higher concentration of espresso and increase the amount of coffee, exceeding this limit will cause a series of problems such as "espresso won't extract properly, after removing the portafilter, the surface of the basket is wet, but the coffee at the bottom is dry, and a bunch of coffee grounds stick to the shower screen."

However, if the amount of coffee used is significantly below the standard weight of the basket, it will lead to severe water accumulation after extraction. In more extreme cases, when you remove the portafilter, a puddle of coffee water will spill out.

(When the coffee dose is below the ridge)

We need to understand that during extraction, the coffee machine releases pressurized water columns. When the extraction button is pressed to stop extraction, the pressure relief valve opens, creating back pressure in the sealed portafilter basket, which expels excess water from the puck through the pressure relief valve. However, when you use too little coffee, the distance between the puck and the shower screen is too large, making it easy for some water to remain in the basket and accumulate.

If you can't determine whether the amount of coffee you're using matches your basket, you can look at the concave line in the basket. After tamping, see if it just reaches the ridge. Too high means too much coffee, too low means too little.

Taking FrontStreet Coffee's daily extraction parameter adjustment as an example, FrontStreet Coffee uses a 20g basket and doesn't use more than 20g of coffee during adjustment. If more than 20g is needed, FrontStreet Coffee will choose to adjust the grind slightly finer. When the flavor profile is close, sometimes we might reduce the dose by a few tenths of a gram, but the amount won't go below 19.7g.

Group Head Pressure Relief

If the group head hasn't been cleaned for a long time, or hasn't been cleaned thoroughly, long-term accumulation of coffee grounds can lead to pipe drainage or drainage function damage, causing excessive water accumulation in the basket after each extraction.

In less severe cases, simply maintaining daily cleaning of the group head and regularly using dedicated coffee machine cleaning agents for cleaning is sufficient. However, if the problem still cannot be resolved, it's recommended to contact customer service for inspection and repair.

Insufficient or Unstable Pressure in Espresso Machine

Insufficient pressure is a relatively common situation with home coffee machines. The pressure during extraction is insufficient or unstable, with the pressure gauge showing "fluctuating jumps."

(For reference only)

The most direct manifestation is that the extracted liquid column suddenly changes from thick to thin, which prevents the pressure relief valve from having enough pressure to draw back, ultimately leaving a large amount of water accumulation after the portafilter is removed.

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FrontStreet Coffee

No. 10, Bao'an Qianjie, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province