DIY Keg Washing Pump

As you may have read in my previous posts, I have now gone from the classic bottle refermentation to the use of kegs and forced carbonation. The improvements in the beers are really noticeable, and after getting used to it the work itself is not complicated at all.

But like everything in the world of beer, this one also requires proper cleaning to be used again and again. But while bottles and fermenters are easily inspected, the kegs are not at all, despite the large inspection hole on my Kornelius kegs.

Analyzing the various possibilities that I had to clean the kegs well and prevent the beers from infections, I found myself inclined to make a pump for automatic washing as built by a friend of mine. Later I also found an article on BrewingBad where there was an explanation of  the realization of a system very similar to my idea.

The idea

The idea is to build a pump that by using a rotating sphere similar to those used regularly on professional systems could spray inside the keg the cleaning liquid for a long time. The liquid must be drawn from a tank in which it will then be poured again creating a recirculation that will reduce the amount of detergent needed.

To this solution it is also possible to add a second cleaning line to connect to the keg connectors in order to allow the washing of the inner pipe (which otherwise would be impossible to clean without disassembling the whole keg).



Copying the system of my friend I decided to use as a tank a simple plastic bucket (I had a 10 liters one) with a lid on which to lay upside down the open keg. The lid must have a hole not only to pass the pipe that goes into the keg but also to allow the collection of the return liquid.

The pump had of course to be able to push the liquid to the top and have enough strength to make the ball work. I decided to take a common Chinese acquarium immersion pump easily available on Amazon. Being submersible it does not need sucking lines and it is equipped with standard ½” threads to mount the pipes or any other standard hydraulic connector. The model I chose is 3800L/H at a cost of 36€.

I took a stainless steel ball on Aliexpress with ½” thread for 16€, along with all the fittings. I chose to build everything in stainless steel for the simple fact that my father had pieces of stainless steel pipe that he did not use, but it is possible to make the entire system with cheap PVC pipes (for this variant refer to BrewingBad blog).

On a T-connector I mounted a 9.5mm John Guest socket on which I can attach tube with the Jolly connectior to attach it directly to the keg for washing the inner tube. I also took caps to close the second line in case I didn’t use it. Since I would have used the same system to wash other kegs and fermenters, I made three pipes of different lengths to adapt to the various situations.

The cleaning liquid

Regarding the detergents to be used I have documented a lot, but in the end I followed a solution similar to what is done on professional systems based on two washes with alkaline first and then acid liquid.

At a local shop I purchased a caustic detergent used in the beverage industry for single phase washing (here the link to their site). The advantage of this product compared to other solutions is that for the washing of tanks and maturers the product must be diluted (from 3% to 5%) in water at room temperature and not hot liquid as with other solutions. This product requires a contact time of 20 – 30 minutes and is harmless on steel and plastic material.

Although declared as a single-phase product, I decided to follow the common practices and do a subsequent rinse with an acid-based product both to remove any limestone formed by the caustic solution and to neutralize any remaining alkalinity in the keg.

For this rinse, I make it last 10 minutes, I’m using common citric acid in 4% solution easily found in any farm shop. It should also be good Saniclean, the non foaming version of the common Starsan, also because citric acid is not sanitizing and therefore I perform also a Starsan wash before using the keg again.

The final product

The result is amazing: the keg stands perfectly on the bucket and to fully immerse the pump inside it 5 liters of detergent solution are enough. I don’t have to do practically anything but prepare the solutions and in less than an hour the keg is luster as a new one. Everything at a very low price.

At the moment I am using this system also with the plastic fermenters and the new stainless steel fermenter (which I will talk about shortly in the next – and last – article dedicated to forced carbonation), and the washing pump works perfectly also with them.

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