Gott Cooler Mash Tun Conversion

I’ve read many web-pages on the subject of converting a 10-gallon Gott cooler (now Rubbermaid) into a mash-tun. I came up with my own approach, which I think is much easier and cheaper too. To begin with, get a 12″ Phil’s Phalse Bottom. It fits a 10 gallon Gott perfectly. The tricky part is always the “bulkhead” fitting, where the wort line passes through the wall of the cooler. Phil suggests using a drilled rubber stopper with a 3/8″ OD copper tube. I think that will leak, especially if you accidentally bash it with the paddle while stirring your mash.

Here’s how I did it:

Start with your basic 10-gallon Rubbermaid or Gott cooler (mine is a Rubbermaid, purchased rather expensively at a restaurant supply.)

Unmodified Gott

I ran the wort line out the spigot hole at the bottom, like everyone else. You have to remove the spigot. The spigot is held on with a large plastic nut on the inside, and a rubber gasket.


Here’s where my method departs from others I’ve seen. Gott has conveniently already solved the bulkhead problem with this spigot. Perhaps we can find a way to leverage their work. Since we were originally just going to throw this part away, we may as well take it apart first (in the interest of science). If you push the spigot button, you can use a sharp knife to cut off the plastic valve that will protrude from the inside of the spigot: The valve core will then fall out the other side.

Spigot DissassemblySpigot Exploded View

To make this into a bulkhead fitting, we need to run a piece of tubing through the spigot body in a water-tight way. For good flow-rate and resistance to clogging, I used the ubiquitous 3/8″OD copper tubing from Home Depot. The spigot body has a hole straight through it that the core used to be in. The hole is too small for the 3/8″ tubing, but the spigot body has enough material that we can enlarge the hole just enough to get a tight fit. I just used a 3/8″ bit in the drill press:

Enlarging the spigot hole

Then you can push the copper tubing through the hole to complete the bulkhead fitting:

Spigot Bulkhead

At this point, I replaced the spigot on the cooler, with the original rubber gasket and plastic nut. Filled with 10 gallons of water, it was water-tight. Nevertheless, to be extra sure, I applied some food-grade sealant around the joint on the inside.

Completed mashtun

And that is basically it. No futzing about with poorly-fitting rubber stoppers, no search for some elusive combination of Home Depot pipe-fittings (I wish I could get all that time and effort back now.)

Install the Phil’s Phalse Bottom inside of the mash tun. A short piece of 3/8″ID plastic tubing will form an adequate seal with the copper tubing on the inside. Don’t bother with hose-clamps or anything, this connection doesn’t have to be water-tight. But it should be firm enough to withstand a bump from the stirring paddle without coming off. On the outside, you can install a valve on the copper tubing to control the flow-rate during sparging and run-off. I used a compression-fit quarter-turn ball-valve. The large port of a ball-value is desirable to avoid getting clogged by bits of grain husk that may get through the false-bottom before the filter bed is set. If a bit of grain gets in there, just open the valve all the way for a second to push it through.


Phil’s Phalse Bottom

29 responses to “Gott Cooler Mash Tun Conversion”

  1. Cool – I did my first all-grain (an oatmeal stout) on the Canadian Thanksgiving weekend using the so-called “Zappap” lauter tun, named after Pappazian (a guru of homebrew, I understand). Anyways, should’ve been a Crapap lauter tun (consists of two nested primary fermenters, the inside one drilled with a few hundred holes, the outside one fitted with a spigot). So it seized up within a few seconds, resulting in me needing to dump out the mash, drill more holes, dump the mash in – at which point it seized up again…so I had to stir the mash throughout the entire sparge. Somehow, I got a half-decent brew out of it, but I am looking for ideas for my next batch – which gets me to the actual point of this: I like your adaptation, and the fact you didn’t come up with a mickey mouse solution (like the suggested rubber bung – I’ve heard of those just plain falling out during a sparge), but also avoided spending a fortune at Home Depot on the plumbing. Nice work – I’ll keep it in mind.

  2. a nice two-fer stop by! I got a great template for my patchbay AND you homebrew 🙂 as do I! love the plans for the cooler conversion. I’m going to set one up ! Cheers 🙂

  3. Thanks for sharing. Great idea for my homebrew ability. We are about to try all-grain so this mash tun will be helpful, not costing too much money, but being good value. Now to find a site for the hot sparge water.

  4. This looks great and you make it look “doable”. We’ve got our cooler, the tubing, but we are getting frustrated trying to get Phil’s Phalse Bottom. Any idea where two guys from Toronto can get the 12″ Phalse Bottom?

  5. I really like your solution to the bulkhead problem. Can you remember what product you used as a sealant?

  6. I got my Phalse Bottom at a homebrew shop in Hamilton. Can’t remember the name, but it was on Upper James.

    I think it’s probably easiest to order them online from the manufacturer, Listermann.

  7. tried making beer years ago and had reasonably good results. anyway like a lot of us life got busy and this enjoyable past-time was put on hold for about 20 years…my circle of friends now have the time and interest to start things back up again… thankfully most of our basic equipment was wisely put in storage…we were on an intermediate level using extracts and small amounts of grain. home for us is just north of toronto and the question is (finally) who would you recomend for supplies in our area… any help would be greatly appreciated.

  8. Instead of making a mash/lauder tun for my first all-grain batch, I got a 24″x24″ grain bag with a real tight mesh and put the mash in my bottling bucket. It went in at 160f and I doughed in and then put a fleece shirt around the bucket & left it for 1hr. I didn’t stir the mash & 1 hour later the temp was 158f I sparged into the brew kettle, no grain came through the mesh bag. All in all, at the end when I measured OG I had a 72% efficiency with starch conversion. The wort was so good I can’t wait for the beer.
    This cost me $5.
    Good luck.

    • I agree. Use a bag. You can purchase a curtain sheer at Wal-mart that is very fine mesh Voile for around six bucks. I use this for the BIAB (brew in a bag) type of all grain brewing. This would work very well in a mash tun.

  9. thanks so much for sharing this info it really helped. i spent over 3 months looking for something this easy. also to doug i got my phalse bottom at my local homebrew shop but there are many cheap places on the internet.

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  12. Damn it! I wish I would have seen this 2 days ago. I just spent a bunch of money on copper tube and fittings at Home Depot. It took me many hours and many swear words to put together a combination of fittings that worked and didnt’ leak. I’m hanging onto the original spigot so I can retro fit it like you have described in case my setup leaks. Awesome setup, man. Thanks for sharing it.

  13. Hi please email me I have some questions for you and I may be able to help you get some Kegs…

  14. I just made a manifold from copper and was trying to figure out the bulkhead, I saw yours and problem solved. Thanks

  15. Hi,
    Thanks for posting this very informative set of instructions. I actually made a mash/lauter tun out of the 7 gallon and it’s working quite well.

    One comment I wanted to make, though, was on the type of sealant that you used. You said you may have used “Plumber’s Goop” as your bulk-head sealant, though I happened to be shopping for food grade/ high temp resistant sealants and Plumber’s Goop actually stated “not for use at temps over 140 degF.” It also stated that it should not come into contact with food, water, or animals. If you ever wanted to switch to a safer sealant, I’d suggest using a different sealant – Permatex “66B (Clear RTV Silicone Sealant). It has the NSF 51 seal of approval for use with foods and beverages at high temps, and it’s waterproof/flexible. You can pick it up a 3oz tube of it at most auto shops and K-Marts at about 4 bucks a pop.

    Thanks again!

  16. this is a great idea. genius.

    My Gott cooler is not very old. it is an Igloo brand and it’s spigot is actually simpler than the design you show for removing (it has a rubber gasket that pops off). Also, if you are skilled with a propane torch, you can heat up the 3/8″ copper (count to five) and jam it thru the spigot housing and avoid using a drill press. This is what I managed to do, but be warned, it only takes a few seconds to get the copper hot enough to melt the soft plastic, so have a bucket of cold water handy if you choose to torch it.(you may want to practice on something of a similar plastic first. and the plumbers goop will make sure it seals.

  17. note: I didn’t use Plumbers Goop, I used a non-toxic JB Weld product (300° F rated).

  18. Just did this, great instructions. My copper pipe fitted snugh into the spigot body w/out drilling, slightly different design from the one pictured above. Worked a treat, expected much more effort here, top work!

  19. Thanks, I just got back from Home Depot trying to figure out what to do, fortunately I didn’t buy anything before running into your instructions. The new rubbermaid has a slightly different spigot, which I ended up sawing off and the remainder work perfectly, as per your instructions

  20. Hello,

    I have a website with a guide on the different types of Igloo cooler parts available. I think it would match well with your page here for a link exchange.

    In a link exchange, each party simply puts a link to each other’s page on their website. This can increase trust with the search engines, increasing rankings for both parties. If you’re interested, send me an email at:

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  21. Thanks for the article, it was great inspiration. Using a standard Rubbermaid 10 gallon, I was able to do the uber-poorman’s mash tun. Just saw off the spigot as you recommend, then use some dishsoap as lube to shove a 7/16″ outer diameter vinyl tube through the hole. Perfect seal. 🙂 You can use a pinch clamp to control flow out of the container for the cheap version, or attach a nylon valve. I used hose barb to MIP on the inside, then FIP to hose barb for the stainless steel braided filter. That way it’s removable for cleaning. Hope this helps those on a budget.

    Using the factory fitting and modifying is what I have been trying to figure out.
    Once you get the copper “stub” out, fitting a valve is easy.
    Thanks so much for helping me get my head out of my ass…

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