Build Your Own Home-Brewing Mash Tun

If you're getting the hang of home brewing and thinking about making the jump from using malt extract to using all grain, you'll need a mash tun. The mash tun is a large-scale filter in which the grain used in your brew will sit while the starch converts to sugar. Following the conversion process, a properly built tun acts as a basic filter that allows the brewer to strain the sweet liquid from the grain. And the beauty of a home-brew tun is that it can be as simple or as complicated as you wish, while still brewing great beer.

You can buy a mash tun from a home-brewing supplier for hundreds of dollars, depending upon how fancy you want to get. Or, you can build a home-brew mash tun similar to the one pictured using a 10-gallon beverage cooler and some parts easily found in the plumbing section of your local hardware store.


• One 10-gallon round beverage cooler
• 12 to 18 inches of 1/2-inch stainless-steel supply hose
• One 1/2-inch threaded ball valve (brass or stainless steel)
• One 1/2-inch MIP x 1-1/2-inch pipe nipple (brass or stainless steel)
• Three 3/4-inch stainless-steel cut washers
• One 1/2-inch female NPT x 1/2-inch hose barb
• One 1/2-inch male NPT x 1/2-inch hose barb
• Two 1/2-inch stainless-steel worm clamps
• One 1/2-inch brass head plug
• Two 1/2-inch silicone O-rings
• Teflon tape


1. Remove the cooler spigot by removing the plastic nut on the inside of the cooler wall.

2. Remove the silicone gasket from the space between the inner and outer wall of the cooler.

3. Wrap a thin layer of Teflon tape around both ends of the 1-1/2-inch pipe nipple, then fit it through the now-empty hole in the cooler.

4. Cut the ends off the stainless-steel braid using a hacksaw or Dremel tool, and discard them.

5. Using a pair of needle-nose pliers, firmly grip the inner rubber tubing of the supply hose and push the braid off it. You should be left with the stainless-steel braid by itself.

6. Insert the threaded end of the 1/2-inch head plug into one end of the stainless braid, and secure with a worm clamp. The head plug will ensure that your braid does not float in your mash water and remains at the bottom of the cooler.

7. Fit the other end of the stainless braid over the barb end of the 1/2-inch female hose barb and secure with another worm clamp.

8. Fit one silicone O-ring and two of the stainless-steel washers on the inside of the cooler, and thread the hose barb onto the inside nipple. The O-ring should be closest to the wall of the cooler.

9. On the outside of the cooler, fit a silicone O-ring and your remaining stainless-steel washer, then thread on your ball valve.

10. Wrap a thin layer of Teflon tape to the threaded end of your male hose barb, then thread it into your ball valve.

11. Ensure a tight fit of all connections, but be sure to not overtighten or you risk cracking the wall of the cooler.

12. Leak-test your cooler using warm water. Most leaks (if any) can be solved by simply readjusting the tightness of the threads on each section of the valve assembly and/or applying more Teflon tape.

13. Enjoy your brew day!

By Andy Hill



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