How to Easily Turn a Water Cooler Into a Mash Tun in 5 Steps

Turning a water cooler into a mash tun is a popular and cost-effective solution for homebrewers looking to upgrade their brewing setup. By repurposing a readily available item, you can create a durable and efficient mash tun that will serve you well in your beer-making adventures. In this comprehensive guide, we’ll walk you through the step-by-step process of transforming a water cooler into a top-notch mash tun, complete with technical specifications, DIY alternatives, and expert tips to ensure your success.

Parts Needed for the Conversion

To turn a water cooler into a mash tun, you’ll need the following components:

Cooler: A 70-quart water cooler is the recommended size for most homebrewing purposes. This size provides ample space for the mash while maintaining a manageable weight.
Bulkhead Fitting with Stainless Steel Ball Valve: This is the heart of the mash tun, allowing you to control the flow of the wort during the mashing process.
CPVC Pipes and Fittings: You’ll need CPVC pipes, elbows, and tees to construct the bottom manifold, which ensures even distribution of the grain bed.
Neoprene Washer: A 3/8″ ID neoprene washer is used to create a tight seal between the cooler wall and the bulkhead fitting.
CPVC Fitting, Slip to NPT Male Adapter: This adapter allows you to securely connect the ball valve to the inside of the cooler.
Large Grain Bag (Optional): Using a large grain bag can help with grain filtration and cleanup.

Tools Needed for the Conversion

How to Turn a Water Cooler Into a Mash Tun

To complete the conversion, you’ll need the following tools:

Drill: A power drill is essential for drilling the necessary holes in the cooler.
Drill Bits: You’ll need a 1/2″ drill bit for the bulkhead fitting, a 3/32″ drill bit for the CPVC pipe holes, and a 1/16″ drill bit for any additional holes.
PVC Cutter: A PVC cutter will help you precisely cut the CPVC pipes to the desired lengths.

Step-by-Step Instructions

1. Installing the Ball Valve

Remove the Cooler’s Drain: Start by removing the existing drain from the cooler.
Place the Bulkhead Fitting: Insert the bulkhead fitting through the hole where the drain used to be.
Attach the Ball Valve: Screw the stainless steel ball valve onto the bulkhead fitting on the outside of the cooler.
Connect the Adapter: Screw the CPVC Slip to NPT Male adapter into the fitting on the inside of the cooler.

2. Building the Bottom Manifold

Cut the CPVC Pipes: Measure and cut the CPVC pipes to the desired lengths for your manifold design.
Drill the Holes: Drill a series of 3/32″ holes along one side of the CPVC pipes, spaced approximately 1-2 inches apart.
Assemble the Manifold: Attach the CPVC tees and 90-degree elbows to the pipes to create the manifold structure.
Place the Manifold: Position the manifold in the mash tun, with the drilled holes facing downward.
Optional Grain Bag: If desired, place the manifold inside a large grain bag to aid in grain filtration.

Additional Tips and Considerations

Use Stainless Steel Components: Opt for stainless steel parts whenever possible to ensure longevity and food safety.
Plan Your Build: Carefully plan the layout and measurements of your mash tun before purchasing parts to ensure a proper fit.
Adjust for Cooler Size: Modify the instructions as needed if you’re using a smaller or larger cooler than the recommended 70-quart size.

Technical Specifications

Bulkhead Fitting: The bulkhead fitting should have a thick wall and a stainless steel ball valve to withstand the demands of the mashing process.
CPVC Pipes and Fittings: Use 1/2″ CPVC pipes and fittings to create a secure and efficient grain distribution system.
Neoprene Washer: The 3/8″ ID neoprene washer helps create a tight seal between the cooler wall and the bulkhead fitting, preventing any leaks.

DIY Approach: Vinyl Tube and Stainless Braid

For a more budget-friendly DIY approach, consider using a vinyl tube with a plastic valve on the outer tube and a stainless braid on the inner tube. This alternative can save you $15-20 compared to using brass components, while still providing a reliable and functional mash tun.

References

By following this comprehensive guide, you’ll be able to transform a simple water cooler into a highly functional and efficient mash tun, ready to take your homebrewing to the next level. Happy brewing!