Making a Homemade Mash Tun

I posted this on my personal website a year ago while making my mash tun.  I thought it was time that I added it to the CSI website.

When I began homebrewing, the only batches I ever made were from malt extract.  This works fine, but as I quickly realized, you don’t really get the color appearance that you are looking for.  So I took a class on “All Grain Brewing” in April 2009 at Maryland Homebrew in Columbia, MD which was amazingly helpful.  It proved to me that all grain brewing wasn’t so tough.  The only problem was, I needed a mash tun.  Commercially made mash tuns can be expensive.  Craigslist is a great option, but in the 9 months that I’ve been searching for one, I didn’t see one come on the market.  So I decided to use my creative side and make my own out of a cooler and some parts from the hardware store.

Below you will find a step by step description of what I did to make my own mash tun.

1)  Find a Cooler that Works for You

I plan on doing 10 gallon batches of beer.  So I needed a cooler that was a little bigger.  The standard 48-quart square coolers or 10-gallon round Rubbermaid coolers were a little too small for what I wanted to do.  I was able to find a real nice 70-quart Coleman Extreme Cooler on for $38 with free shipping.  I looked around at Bass Pro and Walmart and didn’t find anything close to that in price.  So Amazon ended up being the merchant I chose.

70-quart Coleman Extreme Cooler

2)  Shop for Parts to Make Manifold

Luckily there are some web sites out there with information on how to build your own mash tun.  I stumbled across the “Converting a cooler to a mash tun” article on the wiki at  From there, I came up with some ideas on how to convert my cooler to a mash tun.  Here’s the shopping list I went with: 

(4) – 1/2 inch diameter – L-shaped (90 degree) copper slip on elbows
(5) – 1/2 inch diameter- T-shaped copper slip on tees
(1) – 1/2 inch diameter copper slip on coupling
(1) – 1/2 inch diameter copper pipe – 8 foot in length
(1) – 1/2 inch diameter copper pipe slip on adapter with female end
(1) – 1/2-inch diameter brass pipe nipple – 2 inches in length
(1) – 1/2 inch diameter brass ball valve with female ends on both sides
(1) – 1/2 inch diameter brass hose barb adapter with a male end
(2) – 2-inch diameter neoprene washers
(6) – 2-inch diameter fender washers (zinc) with 3/4-inch hole in the middle
(1) – roll of teflon tape (white)

Picture Copper slip on fittings

3)  Cut Copper Pipe

I had never cut copper piping before, but it is real easy using a “Copper Tubing Cutter”.  I picked one up at Lowe’s for around $7.  It is real simple to use.  All you do is measure out the length of piping you want to cut, mark it with a pencil, put the copper tubing cutter on the pipe, tighten it, turn it once, tighten it again, turn it again, and the piece of pipe should fall off pretty quickly. 

Here’s a list of pipes that I cut up:

(2) – 2.75 inch lengths
(2) – 5.5 inch lengths
(5) – 6 inch lengths
(1) – 9.25 inch lengths
(2) – 9.5 inch lengths

Now this is what worked for my cooler.  You will want to measure your cooler to see what works for you.  I hear it is best to keep the manifold 2-inches from the side of the cooler.  With that said, these dimensions worked for me.

Cut up copper piping


4) Modify Washers

This was absolutely the worst part of this whole process.  You have six 2-inch diameter fender washers with 3/4-inch hole in the middle.  Unfortunately the 3/4-inch hole in the middle of the washer is not big enough to get around the nipple.  So you have to expand that hole in the center until it fits.  I used a Dremel Rotary Tool with a tungsten carbide rotary tool bit.  I bought one from Sears because the cutting end was a lot wider on the Sears Craftsman model then the one that comes with the Dremel tool.  You will want a larger cutting end because this is a very long and laborious process. 

Here’s what I learned:

  • It’s not easy
  • It’s not fun
  • Use a pair of vice grip pliers to hold the washers in place and make sure they are secured tightly.
  • Watch your fingers (my hands are cut up)
  • Wear goggles
  • Be patient.  This will take around 10-minutes per washer to finish.
  • No matter how hard you try, the washers will not be in a perfect circle when you are finished.  That is OK.
If you have an easier way of doing this, I’m open to suggestions.

Modified washers vs original washer

5)  Remove Drain Plug from Cooler

This part was a lot easier than I thought it would be.  The drain plug on the cooler is removable real easily.   Just hold the spigot on the outside and twist counter-clockwise while holding the drain on the inside of the cooler in place.  These drain plugs are not in place very tightly, so this shouldn’t take much work.  You sure don’t need a tool.

Twist the drain plug counter-clockwise to remove.

This is what it looks like when it's removed.

6)  Assemble Mash Tun Spigot

Assembling the Mash Tun drain spigot was pretty easy too.  So easy, I forgot to take step by step pictures of what I did.  As you can see from the photo though, I wrapped the threaded end of the brass hose adapter with teflon tape and twisted it into the brass ball valve.  I used 2 adjustable wrenches to tighten them together.  Please make sure that the handle on the valve, when open points out over the brass hose adapter.  This is very important.

Next, wrap one of the threaded ends of the brass nipple with teflon tape and twist it into the other end of the brass ball valve.  A pipe wrench and an adjustable wrench will work here to tighten it up.

7)  Add Steel and Neoprene Washers to Spigot

This step was real simple as well.  Once you are done cutting the steel washers so they fit over the brass nipple, slip 3 of the steel washers on first.  Once the steel washers are on the nipple, slip on the neoprene washer so that it is firm against the steel washers.

One washer on drain spigot

Three washers and the neoprene washer on spigot.

8)  Insert Spigot into Cooler and Secure with Neoprene Washer

The spigot should fit easily into cooler with the brass nipple having about 3/4-inch of thread on the inside.  After putting the spigot in, secure it on the other side with the other neoprene washer.  This will hold in place until you are able to assemble the other washers.

Put spigot through cooler

Secure spigot with neoprene washer inside cooler.

9)  Secure Spigot from Inside Cooler with Washers and Female Adapter

Once you have passed the brass nipple through and secured it with the neoprene washer, wrap then exposed threads of the nipple with teflon tape.  Then add the other 3 steel washers over the nipple and secure it with the 1/2-inch adapter that has female threads on one end.  This is shown in the picture.  Tighten the spigot and the adapter by using adjustable wrenches.

Secure spigot with washers and pipe adapter.

10)  Assemble Manifold and Test to Make Sure it Fits in Cooler

The manifold will go together very easily, as shown in the picture to the right.  This is an ideal set up as allow for maximum draining of your grain bed.  I have been asked if I am going to solder the piping together.  Since the whole purpose of the manifold is to allow for draining of liquid from the grain bed, the piping does not have to be water tight.  In fact, you will be cutting slots into the piping in step 11.  Plus I see a manifold that can be disassembled as a bonus when it comes time to clean.  For the most part the pipes and fittings will be snug enough to have some form and stay together.

11)  Cutting Drain Slots in Manifold

This is where you will need the Dremel Rotary Tool again and it is absolutely important that you wear safety goggles here as metal will be flying all over the place.  Attach an EZ-Lock 1 and 1/2-inch “Cut-off Wheel” to your Dremel.  This will be the tool used to put drainage slices in your manifold.

Once you have the Cut-off Wheel on the Dremel, it is time to start cutting.  I recommend using a medium to high speed setting here.  My Dremel only has 2 speeds so I only have 2 options.  If your Dremel has more, go with a medium setting.  Cut slices into the pipe about every half inch.  Make sure you do not cut straight through the pipe.  Only go in about half way through the pipe.

NOTE:  The copper piping will get real hot when cutting your drainage slices.  Please keep this in mind and wear gloves if your hands are sensitive to heat.

Once you are done cutting the drainage slices in your manifold, I recommend using a rotary buffing tool along your drainage slices to remove any burrs that might be left over from the cutting.  As soon as the burrs are removed, then you are ready to install the manifold into your cooler.  Remember, you want the drainage slots facing down to the bottom of the cooler to get the maximum yield from your grain bed.

Cutting drainage slices into the manifold.

A completely sliced up manifold. Be sure your drainage slices face down in the mash tun before installing it.

12)  Enjoy your Mash Tun and Crack Open a Beer!

And that right there are the 11 moderately easy steps to creating a homemade mash tun.  I know it was a lot of fun for me and very rewarding to create something so cool to use when homebrewing.  The mash tun works out great and I’ve created some awesome beers with it.  So I know this is a good one.

Please feel free to e-mail me with any suggestions that you may have regarding how to more efficiently make a mash tun or with pictures of mash tuns that you have created.

Happy brewing!

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  1. This will be my project for next weekend. Thanks for the post. Have you come up with any alternatives to the washer issue since you posted it? Definitely something I’d like to avoid. Shorter brass pipe nipple, maybe?

    1. So in talking to others in the homebrew club, I found that you can actually buy washers with a center whole larger than 3/4 of an inch. I’d recommend getting something like a 7/8 or just a size larger. You can’t find that at Lowe’s or Home Depot, but I guess you can at pluming stores or online. Let me know how it goes and share any pictures you have.


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