Underback / Wort Grant / Wort Holding Tanks

Underback/wort grant

Underback/wort grant

The beer brewing community has certainly enjoyed labeling brewery-related equipment with interesting nomenclature for hundreds of years.

The Underback is a small, open-top vessel used as a mash volume separation device. It is in place between a lauter tun, mash tun, mash filter, etc. and a kettle. It’s main function is so that the brewer can check on the clarity and color of the wort visually. An underback is integral in maintaining the wort flow, and also saves time when a batch is more than one kettleful.

When a pump is used to move the wort mash from the lauter tun/mash tun → kettle, it is possible to pull the wort from the tun at a rate faster than the grain-bed needs it to flow. This can compact the bed and result in stuck run-off. Besides being challenging to deal with, stuck run-off can also damage the pump.

One solution to this particular brewery problem is to buy a speed controller device for the pump. However, a speed controller is an expensive item. It is also possible to install a ball valve to restrict the flow on the outlet-side of the pump, but this is often a clumsy method to fine tune the flow of liquid. This is why you should look into including an underback / wort grant into your brewery setup.

What Does an Underback or Wort Grant Do?


Stainless Steel Wort Grant

An underback is a vessel that collects wort from the mash/lauter tun. A pump is plumbed into the underback instead of the lauter or mash tun. Gravity then pulls the wort from the mash tun and this minimizes the grain bed from compressing. A float switch can turn the pump on when the underback is full, and this frees the brewer from having to micromanage the procedure.

When the correct volume of wort is in the kettle, it can be boiled. Meanwhile, the wort can continue to run into the underback. The wort in the underback is held at temperature until the previous kettle contents has boiled and been sent on to the fermenter or whirlpool; then the contents in the underback are moved to the kettle.

The first batch of wort moved to the underback is traditionally called first wort. A wort holding tank saves the brewery and the brewmaster a lot of time as the underback can be used to collect the first wort while the other is boiling in the kettle.

Underback / Wort Grant / Wort Holding Tanks should be regularly cleaned as the wort is held at fluctuating temperatures.


  • Capacity: 10L, 20L, 30L, 40L, 50L
  • Wort inlet and vent
  • Glass cylinder for wort filtration observation
  • Thread connection with seals, convenient cleaning, and installation

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