Sometimes the espresso just comes out watery and this is not what any espresso lover likes to see. What happened and how can you fix it?
If espresso comes out of the machine watery, it’s likely the result of a grind size that’s too coarse, a mistake in puck prep or tamping, the roast level or a portafilter that’s not correctly locked into the espresso machine. Channelling can also be an issue.
What do all those things mean, why do they cause your espresso to be watery and how can you fix them? Find out below.
1. Grind Size
The most likely reason you get watery espresso is that the grind size is wrong, likely too coarse. If the coffee particles are too coarse there are big gaps between the particles that let water through too easily. That means the coffee doesn’t get extracted properly and the water just gets through without touching much of the grounds. The water has to extract the grounds quickly to get that thick liquid.
Grinding finer means more surface area on the grounds and smaller gaps between the particles. That means the water flows slower and extracts more from the grounds because there is more water touching the grounds at one time. This means a darker, thicker liquid.
Make sure you use a good grinder. The coffee particles should be similar in size and have little ‘fines’ or coffee dust. A good burr grinder is essential for making good espresso. Blade grinders should not be used to grind coffee for espresso. Check out some of the grinders below that are capable of grinding for espresso.
2. Puck Prep
Preparing the coffee grounds properly has a big impact on how your espresso turns out. The goal is to get the grounds distributed as evenly throughout the basket as possible. All the clumps should be broken up and the grounds should be fluffy.
Try to get the grounds level throughout the whole basket by tapping or shaking the filter a little. Then use a distribution tool and stir the grounds by making small circles all around. Start with the tips at the bottom and slowly work your way up. That should distribute the grounds as well as reasonably possible in a short time.
If the grounds are not distributed equally, the coffee bed will be more dense in some places than others. The water will flow through the less dense areas. Those areas will be extracted and depleted quickly and then just make watery and very bitter coffee. The more dense parts will see less flow and be under extracted adding sourness.
After puck prep, tamp the bed. Tamping is just compacting all the grounds together and getting all the air pockets out. Usually tamping isn’t the main cause for watery espresso but it can contribute.
If there is too much space between all the coffee particles, the water can get through too easily and not enough pressure is being built to properly extract the grounds.
Proper tamping isn’t difficult. You just need a tamper and push down on the grounds in the basket. Try to make sure you tamp straight down. Most baristas agree that 30-50 pounds of pressure is good but there’s no need to measure it. Just push until the bed of coffee stops compacting. Pushing harder than that is pointless.
If you’re not sure if you get it right, it’s possible to get a calibrated tamper that clicks when the right pressure has been reached and you know where to stop. They are a bit more expensive than regular tampers though.
If you think you did everything right, check out the puck after pulling a shot. Can you see any little holes in the surface of the puck that seem to go down to the bottom? This can be the reason for your watery espresso.
Those little holes are called channels. They are basically tunnels through the coffee bed. And since water will take the way of least resistance, most of the water won’t flow through the coffee grounds but through the tunnel. That means most of the water doesn’t get to do any extraction and that means watery espresso.
Channelling can be caused by a few things. They are often the result of an grind size that’s too fine or an unequal distribution of the grounds.
If the coffee is ground too fine, the pressure from the machine can’t push the water through the filter. However, the water will always try to find out. If a little bit flows through a ‘weak’ spot the coffee there starts breaking down and create more space. That means it becomes easier for the water to flow through and the process accellerates, The increased water flow in one spot erodes the coffee there and so it digs a little tunnel. This can happen quite quickly and the rest of the water can flow through almost unimpeded. That means it doesn’t touch any of the coffee grounds, and the espresso becomes very watery.
Grind size is an important factor in channelling but the puck prep is another one and can compound the problem. If the puck is less dense in one spot, that’s where the water will flow.
Not only does this result in very watery espresso, it also doesn’t taste good since most of the grounds are under extracted. This likely results in a cup that’s both sour and very bitter.
Of course, the coffee you use is important as well. A light roasted coffee is often going to produce lighter and thinner espresso than a dark roast.
Coffee grounds have a lot of different compounds that give it it’s taste and texture. If a lot of those compounds are dissolved in a little bit of water, it gets thicker. There are a few things that impact how quickly the grounds are extracted which are described above. Most of which have to do with water contact and getting the right pressure.
The roast itself also has a big impact though. The darker a bean is roasted, the more porous the beans become. That means even the grounds have a more open cell structure and this makes it much easier to extract darker roasts. All those taste compounds can be extracted with little water and that’s why it becomes very thick.
If you want to use a lighter roast, it’s not impossible but it does become more difficult to get a properly extracted espresso. You’ll have to grind finer than for dark roasts and the viscosity will never as thick as you can get with a dark roast but, you might prefer the taste.
6. Portafilter Lock
Make sure the portafilter is locked into the machine tightly enough. If the filter isn’t locked in properly, it means the water can just flow past it. It only has to be a tiny leak since an espresso machine creates a lot of pressure, and any leak will let through a lot of water quickly.
Make sure nothing is leaking past the outside of the filter and if there is, twist in the portafilter a little more.
If there is water leaking past the coffee, it is obviously not getting brewed and you’re just getting water. THat’s obviously not what you want. If you want to brew a americano, there are better ways.