Here is my version of a mini keg set-up to serve home-made beer from 2 liter PET bottles or beer growlers.

It solves a few issues for lovers of home-made and craft beer:

Beer going flat once the growler has been opened.
Having to clean and fill 48 bottles to store your batch of home brewed beer

It allows you to use 2 liter pop bottles (PET) which is cheap or your glass growlers. Apparently you can get 3 liter pop bottles in the US. Or buy 6 litter PET bottles from Tap-a-draft. They use 38 mm caps, same as beer growlers.

You only need a few parts and it requires very little skill.

I assume you already have a CO2 tank and regulator

DON'T use this without a regulator set at less than 40 PSI !!

See this Instructable to see how to make the mini CO2 tank setup

Step 1: Tools and Materials Required

7/32" drill bit
Flexible plastic glue - suitable to glue Vinyl.
1/8" Internal diameter, 1/4" Outer diameter Vinyl tubing - at least 4 feet
0.17 ID, 1/4 OD will also work and it is easier to find
1/4" ID, 3/8" OD Vinyl tubing - 1 foot
You'll find this at any hardware store and it cost less than $1 per foot.
1/4" to 1/4" Push-to-Connect Union
You can get this on ebay - search for "Push to connect 1/4 union" - and look for the cheapest one.
Picnic tap
From ebay or your local homebrew shop
1/2" Hose clamp (or use a Wire clamp tool - see here how to make your own)
Vinyl spray paint
Auto part stores carry this in the body repair section

Step 2: Drill the Cap

Drill two holes in a pop bottle cap - evenly spaced. Drill from the outside in.

Use a sturdy cap - not the soft, floppy ones - like you find on Coke bottles.

I bought a bunch from my local homebrew shop.

Step 3: Cut Tubing

You will need three vinyl tubing parts:

a Whip that will be connected to your CO2 regulator. It consists of 2" of the larger 1/4" ID, 3/8" OD tubing glued onto / over a long length of the smaller tubing.
This length depends on how far your CO2 tank will be positioned from your PET Growler. Ge generous - you can always make it shorter or just coil it up!
a Beer tap line to serve your beer. Like the Whip, it consists of about 24" of the smaller tubing glued to 2" of the larger tubing to connect to the Picnic tap.
a CO2-In line to get co2 into the PET bottle. 6 to 10 inches of the smaller tubing

Cut one end of the 2 and 3 above at a sharp angle to help you get it through the holes in the cap.

Step 4: Pull Tubing Through Cap Holes

Pull the Beer tap line and CO2-In lines through the two holes in the cap.

Pull them from the outside to the inside.

Put a drop of liquid soap on the tubing to make it slip through easier.

Push the sharp end into the hole and grab it with needle nose pliers to pull it through.

Pull the Beer tap line through by about 12" so it almost touches the bottom of the bottle (but won't suck up the sediment)

The CO2-In line only needs to go in by about 2"

Step 5: Glue Bigger Tube to Smaller Ones

Glue one of the 2" pieces of the larger tubing over the the Whip and one over the outside end of the Beer tap line.

You need the bigger tube to go over the barb on the regulator and on the picnic tap.

Put some glue on the end (1/4" ) of the smaller tube and slowly push it into the larger tube WHILE turning it slowly to about 1/2". This is to spread the glue.

Leave for a day to dry.

Step 6: Attach Picnic Tap and CO2 Regulator

Push the Whip over the barb on your regulator and the Beer tap line over the barb on the Picnic tap.

Put a clamp on each. I use a wire clamp tool that I made myself. It makes a clamp with a very low profile and seals better than the screw clamps, but either will do. See how to use it by Googling "Wire clamp tool" or whatch these Instructables.

You could also put some electrical tape over the clamps to prevent injury from the sharp points.

Step 7: Paint the PET Bottles

Beer do not like sunlight ! That is why beer bottles are brown.

To prevent light from getting to my beer, I used Vinyl spray paint to colour my PET bottles. I think normal spray paint will crack or not stick to PET.

In order to see inside the bottle when I fill it, I first put a strip of electrician's tape down the side. This leaves a clear see-through strip to monitor contents

Step 8: Test for Leaks

To test for leaks you can either immerse each joint under water and watch for bubbles or make a leak detector liquid by mixing 50/50 liquid soap and water. Apply with a brush and watch for bubbles.

Step 9: How to Use

If you have a kegerator for your beer, feed the Whip into it and attach to the CO2-In line with the "Push-to-connect Union".

Screw your PET-a-draft onto a bottle full of your naturally carbonated home-brew.

Open the CO2 AFTER you've set the pressure to 10 to 15 psi. (PET bottles will burst at 120 psi. The cap may pop off much earlier. No need to go over 40 psi.

Wait a few hours to allow the beer to settle down after all the movement.

Pour a beer - depress the picnic tap ALL the way to reduce foaming.

Enjoy!

Step 10: Make One for Beer Growlers or 6 Litre Bottles

You can make a similar PET-a-draft to use on glass growlers. Just make the Beer tap line shorter to reach the bottom.

You need a sturdy plastic cap - not the hard Bakelite or metal ones you normally find on growlers.

I ordered mine from Tap-a-draft - see picture.

If you want to have more than one beer available on tap in your kegerator, you can get a "Y push to connect" to spilt your CO2 line. They also sell a plug you can use when one of the ports is not in use.

Step 11: Convert Tap-a-draft

I also made a dummy 8 gram CO2 adaptor to use my large CO2 tank with my Tap-a-draft system.

This system uses small 8 gram CO2 cannisters to push the beer and that gets expensive.

For this I bought a "Push to connect" with a 1/8" NPT tread on one end.

Drill a 11/32" hole in the bottom of an empty 8 gram CO2 cannister and fill it about half way with "J-B Kwik Weld".

Stick some tape over the hole and set it upright to dry for a day.

Then drill the hole again with the 11/32" bit. Clear out all debris to prevent it from clogging the system!

Put some "Pipe joint compound" (not teflon tape) on the threads of the "Push to connect" and force screw it into the J-B filled hole to cut its own threads.

Drill out the bottom of the cannister holder to allow "Push to connect" to stick through.

Now I can connect the Whip to this setup and not buy 8 gram cannisters anymore!

Step 12: Make a Tote to Carry This to the Party!

See this Instructable on how I made a Party Tote to carry your PET-a-draft to the party, keep it cold and make dispensing easier.

See this Instructable to see how to make a mini CO2 setup using a 20 oz. paint ball tank and mini regulator.

Step 13: Use a CO2 "Charger" / "Injector" / Tire Inflator If You Don't Have a CO2 Tank and Regulator

Before I spent the money and time to make a mini CO2 setup, I used a CO2 Charger to push and preserve my homebrew.

Bike shops sell them as tire inflators. Some use 16 gram CO2 cartridges, but I chose one that uses 12 gram cartridges. They are easier to get hold of because air pellet guns use them as propellant - even Walmart carries them.

They are made to thread onto Schrader valves. Ordered "Aluminum tubeless valve stems on ebay. C$4.00

After unscrewing and removing everything from the valve stem, I cut off the large part using a dremel tool.

Then insert and clamp into 1/4 ID vinyl tubing, which again is glued onto 4 inches of 1/4 OD vinyl tube.

This is inserted into the "Push-to-Connect" Union on the PET-a-draft.

Every time after pouring some beer, give it a short pssst to restore pressure in the 2 litre bottle.

Only drawback of this setup is the cost of the cartridges - C$1.00 each.

Introduction: PET-a-Draft Mini Beer Keg System