DIY Mash Tun

After nearly a year of making homebrew from kits (read my reviews) and although I’ve enjoyed that way of making beer, I have been making by own DIY microbrewery to make  all grain beer.

There are many resources for this and believe it or not it, it’s not too difficult, even for a DIY novice like me.

Here is what I did and the parts required, the cost of this came to around £30:


All the copper parts used are all for 15mm pipe and remember,  measure twice, cut once.

  • Cool box
  • 2m Copper pipe – you will have plenty left over for other projects
  • Copper elbows and tees
  • Ball valve tap
  • Tank connector – Available pre drilled for the copper pipe from Copper Kettle Homebrewing
  • BSP socket connector, only required if your tap is male ended


  • Junior hacksaw
  • Pipe cutter (not essential but a lot easier)
  • Drill
  • 22mm holesaw
  • Adjustable Spanner
  • PTFE tape
  • Vice (useful)
  • Measuring tape

Here is the finished manifold

DIY Mash Tun Manifold

1. Manifold

Firstly measure the internal width and length of the cool box, this is to see what size the pipe needs to be cut to. Leave about 1cm gap around the manifold, so bear this in mind for your measurement of the pipe.

Cut the pipe into 4, the lengths and width..

Now you have the basic frame, connect using 4 elbows and place into the box to see the fit, adjust if necessary.

Take 1 of the width pipe pieces and place the tee piece where you want this to be, now bear in mind this is where the tap will be connected so adjust to where this will be, mark out on the pipe with 1cm less to adjust for the connection to the tee, then make 2 cuts, attach the tee and fix to the other sections and see how it fits.

Measure from the tee to the opposite wall, this is the tap section, mark it out ready to cut, useful to use a piece of pipe to get the idea of where the connection will go.

2. Cool Box Tap

OK, step 1 completed and now on to attaching the tap to the cool box, you have measured out the centre from the pipe for the internal wall of the mash tun, now measure the outside from the ground and mark where the hole will be cut, this is important to allow clearance for the pipe of the floor of the box internally, also remember the floor of the box is lower than internally for your measurements.

Take a drill and attach the holesaw and slowly drill through the outer wall, my cool box had polystyrene insulation so went through quite easily and continue through to the inner wall until hole drilled out.

I removed the inner part to connect the tank connector, now place through the hole with the male thread on the outside with the washer against the inner wall, place the manifold in and connect to ensure the exit pipe runs through the connector before fixing in place.

Take the PTFE tape and wrap round the thread a good few times, check the direction is also correct to avoid unwrapping it when connecting, this will help prevent leak, assure me as I forgot first time round 🙂

Now fix the nut on and tighten, I used a spanner to make sure it was firmly in place, place the inner part back in and fix in place.

There you go, a working mash tun to get started with all grain beer brewing.

As my tap had a male thread I attached the socket connector and then wrapped more PTFE tape on the tap thread and connected the tap to it.

3. Test for Leaks

As I mentioned, PTFE tape is your friend here as my first test did leak, fill the cool box with enough water to cover the connector and check for any drops of water, tighten the nut further if anything leaking and then you should  have a basic mash tun cool box conversion.