Why Is My Espresso Puck Wet? Causes of Slow Extraction and Water Pooling in the Portafilter

Understanding Espresso Extraction: Why Your Puck is Wet and Loose

Normally, after extracting coffee, the coffee puck should be relatively dry and come out as a solid, intact block. However, we often find that after extraction, when we remove the portafilter, there's a significant amount of water accumulated in the portafilter basket. The coffee puck is wet and loose, and when knocked out, it fails to maintain its block form.

Although the extracted espresso won't necessarily taste bad, the probability of it tasting unpleasant is quite high. Therefore, we need to identify the problem and make timely corrections! Let's first briefly understand the operation process of an espresso machine!

When we lock in the portafilter and press the extraction button, the coffee machine uses pressurized water columns to extract the coffee puck. When the extraction ends and we release the extraction button, the pressure relief valve opens, creating backpressure that removes excess hot water from the portafilter basket through back-suction.

If water accumulation occurs in the portafilter basket, it means the coffee machine failed to completely suction out the excess hot water, which is why we can see a large amount of accumulated water when we remove the portafilter. There are three main reasons that can cause this situation, the first two of which FrontStreet Coffee considers the most common types: grinding too fine and using too little coffee!

1. Grinding Too Fine

When the grind is too fine, the speed at which hot water passes through the coffee bed is significantly slowed because the reduced particle size narrows the gaps through which water can flow. If the grind becomes fine enough, the coffee liquid will even be released in drops rather than a steady stream.

This situation leads to large amounts of hot water accumulating in the portafilter basket after extraction ends. Because when we stop extraction, much of the hot water cannot pass through the coffee puck in time due to the narrow gaps. Without pressure assistance, this water can only remain in the portafilter basket, and the back-suction cannot remove it all, which is why the removed portafilter still contains a large amount of accumulated water. Then, because the water content in the coffee puck is extremely high, its stability decreases, resulting in a very loose consistency when tapped out!

In other words, the finer the coffee grind, the more likely water accumulation will occur. When water accumulation appears, we can observe the extraction time of the coffee liquid to determine if the cause is indeed too fine a grind.

2. Insufficient Coffee Dose

Each portafilter basket has different optimal capacities depending on its volume! When we use significantly less coffee than the recommended amount for the portafilter basket, the coffee puck, due to insufficient thickness, will create a distance from the shower screen.

When the coffee puck is too far from the shower screen, not only does extraction difficulty increase, but it also prevents the shower screen from completely suctioning out all the hot water from the portafilter basket during pressure relief, because there's simply too much hot water! This is what creates this situation.

Therefore, FrontStreet Coffee suggests that when extracting coffee, the amount of coffee used should ideally fluctuate within a small range of the portafilter basket's recommended dosage.

3. Insufficient Pressure

The issue of insufficient pressure often appears in some home espresso machines! Because many home machines don't provide stable pressure supply. Although they can deliver high pressure initially, it quickly drops significantly, like a roller coaster. The level of pressure determines the strength of the back-suction force - the lower the pressure, the weaker the back-suction force, naturally making it impossible to completely suction out all the hot water from the portafilter basket.

In addition to this, the coffee machine's pressure may also be unstable right after startup. However, this is a normal phenomenon - simply preheating for 20-30 minutes will help stabilize the pressure.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473