Over the course of writing The Frugal Homebrewer’s Companion, I discovered that more often than you’d think, the cobbled-together self-made equipment just isn’t worth the price, effort, or quality. Mash tuns, however, pose a problem and have frustrated me no end–coolers that just don’t have the capacity you want, are expensive, unfriendly for cleaning, and perhaps overkill on the insulation. Further, a good false bottom costs a pretty penny and the ol’ braided-metal-hose filter has terrible efficiency and wears out in no time at all.

Behold–the 55 gallon HDPE (2) (food grade plastic, a former LME barrel) “Rain Barrel” Mash Tun, cut to 37 gallons (to aide in stirring and mobility) and fitted with a 19″ stainless steel mixing bowl, set into the 22″ bottom.

The largest false bottom I can find on the market is 15″, and I wanted to fully cover the bottom for maximum efficiency. McMaster Carr sells 36×40″ sheets of perforated metal, but in addition to being rectangular–and $108–I didn’t want to figure out how to created a concave false bottom from these sheets.

I figured the long “slot” cuts would be faster and easier than drilling holes, not to mention more efficient (more flow per hole, less net holes). We created a kind of herring bone alternating slant pattern to best maintain the structural integrity of the bowl itself. We were a bit worried about the overall thinness of the bowl, but anything thicker may have proved problematic for cutting through, as we went through a number of cutting disks:

We created a tight seal on the drain so that it would hold a siphon as best as possible, rather than try to drive the drain into the side of the bowl. In retrospect, this was not such a good idea because the lack of flow in the grain bed prohibits siphon action, but a simple pump can be used to draw out the last of the sparge.

Three screws and wingnuts were placed through the lip of the bowl just to ensure it would hold tight to the bottom of the barrel and not allow grain through. This was perhaps overkill, two may have sufficed, and does make removing the false bottom a bit troublesome, but then again, you only do it once per brew, so who really cares.

A simple test of the false bottom looked like we had it doing what we wanted. The idea behind the slot pattern was more at the edges–for the rate of flow to favor the sides in order to best prevent channeling.

Mashed 68 lbs. of grain, 85 of which was malted barley, 15% rye and had no issues with volume, the liquid did not even go as far up as the rope handles.

Sparging was a breeze, the relatively narrow outlet (1/2″ drain) slowed the process down, but the flow was brisk and the sparge was finished in 45 minutes. I kept a good 4″ layer of water on top of the sparge at all times and suffered zero channeling without any need of stirring.

After all was done, the mash tun performed exceedingly well, providing 85% efficiency, roughly the same I experienced with my four cooler mash tuns this has replaced. Total cost of project:

$20 – used malt extract food grade barrel. $20 – stainless steel mixing bowl from restaurant supply store. $20 – miscellany copper piping and elbows. 4′ of rope. $20 – drain and barbed hose fittings. $20 – many, many cutting wheels.

TOTAL PRICE – $100

Roughly the same price of a single cooler-style 10 gallon mash tun, but with quadruple the capacity.

Check out my book, The Frugal Homebrewer’s Companion for more on hardware and the brewing process in general.