Homebrewing DIY: Building a Mash/Lauder Tun out of a water cooler

I have decided to move into All Grain brewing and leave the extract behind for the time being. I have really gotten into brewing and All Grain is more work, but gives you the most control of your beer. Instead of buying a bag of pre-extracted sugars from malted grains, in All Grain brewing you extract all the sugars from the grains yourself.

To aid in this process, you need a container for extracting the sugars from the grain (mashing) , a Mash Tun, and a container for separating (sparging) the sugary water from the grain husks, a Lauder Tun. Orrrr, you can be creative and use the same container for both mashing and sparging, and you can even build it on the cheap with common plumbing equipment and a water cooler. A cooler is ideal, because you need the insulation to help maintain your desired temperatures throughout the mashing and sparging processes. I just built a mash/lauder tun and took some pics of the process.

Here are the parts you will need:

a 10 gallon cylindrical water cooler:

a 1/2″ ball joint brass faucet

a 1/2″ thread brass nipple ~1 long

a 1/2″ to 3/4″ hex pipe bushing

a lint trap

a 1.5″ recessed plastic washer

2 1.25″ rubber washers

a 3/4″ faucet thread to 1/2″ swivel hose adapter

some 1/2″ interior diameter plastic tubing

So, those are the parts… assembly is pretty straight forward. Here goes:

Step 1: Remove original plastic spigot from water cooler
I have to use a wrench on the inside locknut, it was on there tightly!

Step 2: assemble the washers for the outer hole
Simply fit the rubber washer inside the plastic washer. If you can find them, just get a large rubber washer that will fill the entire outer side of your cooler’s spigot hole. I couldn’t find the right rubber washers, so i improvised with a plastic/rubber combination.

Step 3: place the washers in the outer side of the spigot hole

Step 4: thread the brass nipple into the brass spigot
You can use teflon tape on the thread of the nipple if you want to. Not a bad idea, but i didn’t have any teflon tape.

Step 5: attach the lint trap to the hex bushing
remove the lint trap from the packing and straighten it out. Be careful, stray strands of the steel threads can be sharp!

place the threaded part of the bushing inside the lint trap and then wrap the rest of the lint trap opening around the bushing. Then using one of the zip ties provided with the lint trap, secure the lint trap to the bushing.

Step 6: attach the trap and spigot to the cooler
If you have some Plumber’s Putty, i recommend lining the cooler’s spigot hole with a thick bead of it. this will ensure you will not have any leaks!
stick the spigot with attached nipple though the front of the cooler’s spigot hole, then screw the bushing with attached lint trap onto the extruding thread of the nipple on the inside of the cooler.

Step 7: attach the hose adapter

Step 8: attach the hose to the adapter

So that’s it. Not too complicated, but it makes a great mash/lauder tun on the cheap. I just made my first batch with this baby yesterday, and it worked like a charm. So grab a water cooler, make a run to the hardware store and start mashing!

18 Responses to 'Homebrewing DIY: Building a Mash/Lauder Tun out of a water cooler'

  1. Nick Kirkes says:

    hey jonathan, just curious if you’ve put this to use yet and if there was anything you’d change. thanks for the detailed pics and description.


  2. Hey Nick,

    I have been using a lot lately, and it hasn’t let me down. If you do go this route, don’t forget the plumber’s putty to seal the spigot hole. I didn’t use any initially, but when i tested it out with water (also a a good step before your first batch) i noticed a small leak. I just took off the spigot, put a thin ring of plumber’s putty around the perimeter of the hole and reassembled the spigot. Not a leak since.

  3. Yu-En Hsu says:

    Much simpler design.. I like it. Did you get all your parts from Home Depot?

    What kind of effieciency did you get with this setup?

    Do you use it to batch sparge?

  4. I was able to get all the parts at Home Depot. I forget the total bill, but I think it was around $65 for everything.

    I have done both batch and fly sparging with this. When I fly sparge I average about 80% efficiency. When batch sparging i average about 70%.

    I have had a few mashes come in about 60%, but those were mashes with several rests (and i missed temps so i had to add more hot water)… ended up having too much water to be able to sparge!

    When used right, this has been a great tun. I think the more complicated mashes need direct heat :)

  5. Yu-En Hsu says:

    Thanks… I’m planning to do my AG on a Stout recipe by using batch sparge method. I’ll need some practice to get the efficiency to stay consistent.
    Thanks for posting this up.


  6. this looks great. I have a cooler that does not have a native spigot so I will have to do a thicker wall but I am going for it.

  7. went great. I think the lint trap is genius. now I am making much bigger extractions!

  8. Mark says:

    So you don’t need a false bottom for this? I feel like even with the just the lint trap, the grain would compact onto the lint trap and slow your flow down a significant amount even if you keep a decent amount of foundation water in the mash tun.


  9. Jonathan says:

    A false bottom would definitely be a nice thing to add, but I have been fine (until recently) without one. For infusion mashes, the rigidity of the grain husks settle nicely into a firm filter bed and keep the mash out going smoothly. However, I have been into large decoction mashes lately, and the boiled (softer) grains seems to clog the metal filter more and more. I have been thinking about making a false bottom. Perhaps using a layer of very fine steel mesh sitting on top of a layer of rocks. A friend of mine does this and really likes it.

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  13. Stefan says:

    Are there any issues with putting hot water into the plastic cooler? Any off tastes?

  14. i haven’t had a problem. the cooler is capable of handling boiling water without a problem. as long as the plastic doesn’t melt, the water/mash will be fine. obviously, don’t use this tun as a kettle :)

  15. Joel Crowley says:

    Just made one of these today – tomorrow is my first brew to test it out. Looks like the design of the cooler has changed a bit it took a little more creativity to make it work….

  16. Dave says:

    Is that spigot lead free? I’ve been having a heck of a time finding one that’s lead free

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  1. […] icing the beer in summer heat. Perviously, I just put the beer in my cooler and add ice. The same cooler I converted to a Mash/Lauder Tun a while back. It worked decently well, but since the carboy stuck out over the top of the cooler, […]

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