Coffee Data Science

Fixing Decent Espresso Waste Valve

Maintenance!

Robert McKeon Aloe
4 min readAug 27, 2024

After some travel, I returned home excited to have some espresso from my Decent Espresso machine. However, I started to notice that I was running out of water in the tank very quikcly, and the waste water try was filling up almost completely for each shot. In fact, I had a few problems with the waste water overflowing that I had attributed that to user error. Little did I know, it was a lack of maintenance.

First, I collected some data. My shot profile is different, so maybe that was why. I measured the amount of waste water after one shot.

I ended up with 261g of waste water for a 3 minute profile that produced 24g of espresso.

I checked in with the Decent user forum, and someone said it sounds like the waste water valve. I admit, I haven’t been running the clean cycle as often as I should, but I will after this.

I was sent a video to watch on how to clean the valve, and I got to work. It was pretty straight forward, and the cleaning was also normal espresso machine maintenance.

I had to get inside to the part by the yellow and green wire.

I pulled it out, and sure enough, the valve was covered in residue.

I cleaned out it real good. While I was scared to try teardown maintenance I had never done, I was glad I did it.

Then I was able to put the part back in.

I wanted to better understand if there was a symptom in my shots that could better show this problem because I had continued to adjust my profile not knowing my shots were slowly changing. It seems shot time was increasing over time even when I went to a faster flow profile.

Additionally, the first shot of the day ran longer than other shots. I looked at the average times for the first shot of the day compared to the rest. The first shot of the day was on average 30 seconds longer than later shots.

So I learned the same lesson as before: maintenance. Run the clean cycles. Use the cleaner. And I should probably look to clean this valve every few years. As a point of reference, I have had the machine for 2.5 years now.

If you like, follow me on Twitter, YouTube, and Instagram where I post videos of espresso shots on different machines and espresso related stuff. You can also find me on LinkedIn. You can also follow me on Medium and Subscribe.

Further readings of mine:

My Second Book: Advanced Espresso

My First Book: Engineering Better Espresso

My Links

Collection of Espresso Articles

A Collection of Work and School Stories

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Robert McKeon Aloe

I’m in love with my Wife, my Kids, Espresso, Data Science, tomatoes, cooking, engineering, talking, family, Paris, and Italy, not necessarily in that order.