Plastic bottles used as mini kegs

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Home brewing of beer is an engaging and rewarding hobby, I'm fairly sure we would all agree with that, but at times it sure could do with a bit of an image makeover, particularly when it comes to the presentation of the finished product.

Home brewing with style

When I started bottling in two litre plastic PET growlers I knew that there would be a problem when it came to pouring the beer. For starters the bottle is large and generally requires two hands to lift into the pouring position, also its quite slippery due to the condensation that forms on the outside of the cold surface. Secondly, and this is the more important, the sediment will mix in with the beer as the bottle is tilted, resulting in a cloudy brew.

I suppose two handed pouring of a slippery plastic bottle could be made to look elegant but it is something I would sure have to work on, and possibly I could learn to convince myself that the sludge does not affect the finished product but in my opinion the awkward pouring and the cloudy beer merely reinforce the average persons conception of the "home brewer". A blue singlet and strong body odour would just about complete the picture!

Perhaps I'm being a bit unkind, after all beer is not the drink that is generally associated with dinner jackets and elegant dining but in my case, I sure wanted to do better than those early days with plastic growlers. I am not a sophisticate but not a yobbo either

Dispensing beer

Beer is only going to leave the bottle by one of two ways, either poured or pumped. I have already pointed out the problems with pouring two litre plastic bottles so it wasn't too hard to arrive at the conclusion that I was going to have to pump it.

(close up of pressure gauge)

Well, not exactly pump, more like push. Using a brass fitting and some 1/4" copper tube, I made a dip tube that fitted through the cap of the bottle and reached down to within 1/2" of the bottom. Fitted into the brass fitting was a Schrader valve to which I could connect a source of pressure. When this source of pressure pressed down on the surface of the liquid in the bottle, the liquid would be forced up the dip tube and out, what could be easier!

(compressed air set up)

The Challenge

After messing around with this for a while now, I think that splitting the atom may have been the lesser task but I do think that I have made some progress. The first problem is what to use as the source of pressure. My initial thinking was to produce a system that would allow the user to disconnect a half consumed bottle from the pressure and allow it to be placed in the refrigerator for later use. This dictated that the bottle remain sealed to prevent the beer from going flat. The Schrader valve and a tap in the outlet of the dip tube kept the pressure in so the obvious choice for the pressure source was CO2, however this is not easy to come by in small cylinders other than the "bulbs" that supply paint ball guns and soda siphons.

Small cylinders of CO2 welding gas are available, complete with regulators. I have been informed that the CO2 is the same as food grade and I hope that this is so because I decided to use this as my source of pressure. It is important to realise at this point that I am not using the CO2 to carbonate the beverage, this has already been achieved by the secondary brewing process in the bottle, it is merely supplying the energy to push the liquid out of the container. This is not the case with keg beer, where the applied CO2 also does this but carbonates the beer as well. The main reason for using the gas was as a preservative for the beer by excluding oxygen.

The first prototype with water worked well. I thought the cap and fitting seal would prove to be a bit of a problem but this has not been the case. I punched the appropriate size, 3/8", in the cap with a wad punch and fitted a backing nut to the inside of the cap. It has withstood a test pressure of 30 psi with no problem so that was easier than I anticipated. The amount of pressure required was a bit of a surprise, anything over 10 psi and basically you have re-invented the fire extinguisher, best results seem to hover around 3 to 5 psi, however my pressure guage is starting to take guesses when the readings are this low so the actual figure may well be a bit different.

Working prototype

(Filling with ice)

Before a full on test under actual conditions could be applied a few more problems needed to be addressed. The bottle should be kept cold during the consumption of the beer and the solution is, of course, ice. I had an insulated drink container and looked around for a tap and fitted this. It was done on a bit of a skinny budget so not necessarily the finest materials were being used, at this stage I still wasn't sure that it was going to be a reliable system. I connected the outlet of the dip tube to the tap using PVC tube and all was in place for the first run through.

(Initial experiments)

I don't like my beer to be over carbonated so uncapping a recently brewed growler produced a small satisfying hiss. I inserted the dip tube and rotated the bottle into the cap and gave it a moderate tighten. At this stage I did not have a pressure guage in the line, so I gave the regulator a half turn, heard the surge of pressure from the bottle, confidently held a chilled glass under the spigot and opened the tap.

It only took about twenty minutes to clean most of the beer from the ceiling and kitchen and happily I was home alone. I didn't need to be Einstein to realise that the pressure was a touch on the high side. For the second attempt I reduced the pressure to zero, then opened the tap and gingerly applied the merest turn of the regulator. I was rewarded with a smoothish flow of beer and a glass full of foam, but this settled down and the finished pour was good, albeit with a large head.

As I mentioned in an earlier article, I only brew extract kits, mainly Coopers Lager so I was fairly confident that the beer would be to my taste and not be too affected by being pushed out of the bottle instead of pulled out by gravity, in fact it tasted better but this might be put down to the general euphoria of success and the fact that I finished the growler.

(Ready to load)


I fiddled around with the various bits over the next week when to my astonishment, the CO2 ran out. At forty bucks a throw these things would cost me more than beer so I looked for an alternative. The cylinders are disposable (can you believe it!) and are not designed to be refilled so that was out of the question. I now decided that I would never have the problem of a half finished growler thus the need for CO2 to preserve the beer would not arise, so I decided to use compressed air. Because I had already invested in the cylinder and regulator and because I am ashamed to be part of the generation who inflicted the disposable mentality on the world, I decided to re-use it.

I won't go into the details of how I did it because it may not be legal, however I do have some experience in pressure vessels so I wasn't fazed by filling it with 90 psi air from my home compressor. I repainted the cylinder to eliminate any confusion as to its contents. A friend gave me a small pressure guage from a beer kit he had but no longer used and I incorporated this into the setup as shown in the photo.

At this point I also experimented with a small double acting bicycle pump to see if that would be capable of supplying the necessary pressure and volume of air required. The result was a resounding yes, a few gentle strokes with the tap open resulted in a smooth flow of beer that stopped almost immediately when the pumping stopped. The only downside is this is the perfect solution only if you have three arms, one to pump, one to operate the tap and the other to hold the glass. I toyed with the idea of eliminating the tap and just having a spigot but there are problems with that and the compressed air worked fine so I stuck with it.

Pressing on

I was much encouraged by the whole project and had quite a few pleasant afternoons fiddling with the gas pressure, pouring the beer and testing the result. This important research could have gone on indefinitely but for the sarcastic comment that I had hardly done much to improve the image of home beer brewing, and as I stepped back to review the whole project, I had to admit that the criticism was warranted.

What had been a cosy little bar in a corner of our sun room now looked like an experiment in low temperature physics with buckets of ice, tubes, pumps and cylinders scattered all over the table. I suppose me in the middle of all this with a happy smile on my face didn't help much. At least the singlet and body odour were missing.

(Working protoype)

I'm not overly smart but I can tell when it would be a good time to lift my game, and "right now" obviously was. I decided to go the whole hog and build a system that would enhance the bar, work reliably and improve the image of brewing, hopefully the last would improve mine as well.

I purchased a ceramic eight litre water filter because I liked the look of it, removed the plastic innards and made an insulated removable liner of sufficient dimensions that a two litre growler would fit with roughly a half inch of space all around. This would allow the ice to come into contact with the whole bottle. Like most Australians I cannot abide warm beer and anything above 34 degrees is warm beer.

I removed the plasticky tap and replaced it with a brass garden tap I purchased at the hardware store. I sawed off the pipe thread that the hose attaches to and gave it a polish. I had to modify the connection at the rear of the tap but working with brass and copper is relatively easy. I use a very low temperature silver solder on the joints as lead free is a must. The tap was then epoxy glued into place. I had a lovely old brass door knocker in the shape of a lion's head and this so balanced the brass tap that I epoxied it to the face of the container. This so inspired me that I designed a label around it and consequently the beer is known as "Lion's Head Lager". I drilled a hole in the back of the water filter, cleverly now called "The Beer Dispenser" and glued in a fitting to take the pressure hose. Annoyingly, the manufacturers of the water filter felt the need to advertise their name prominently on the front so this I covered up with some sisal rope. Finally, to make sure there was enough clearance under the tap for the various glasses I have, the whole unit was mounted on a timber fruit bowl that I scavenged from the local opportunity shop for five bucks! (Who said I was cheap!).

(Attaching the growler)


The beer is good thanks to the efforts of Coopers but I must say that the taste is enhanced by the dispensing system. Just as a quality champagne needs fine crystal rather than a paper cup, a well crafted beer will look, smell and taste far better when it is well presented in a glass. All of the sediment is left in the bottle and the beverage is clear and sparkling. Chill haze appears to reduce with bottle ageing. Unfortunately it is absolute murder on the labels I make and I have yet to lick the waterproof problem, suggestions appreciated!

The system has the advantage over a keg in that it is portable and quite small. It fits on the end of my bar with a relatively small footprint and I think it looks good even when not in use. The biggest improvement I could make would be a closer tolerance regulator as the pressure is quite critical, especially for the first glass but I believe the same can be said for keg beer as well. As a talking point with my non brewing friends, it has gone over very well (pack of freeloaders!) and more than one are considering brewing themselves.

The two litre PET bottle is a magnificent container for the home brewer. Had it been invented in another, earlier era it would have been only for the exclusive use of kings and the rich. I have not had any beer "skunk" due to light nor taste "off" caused by oxygenation but I have noticed that many experts on the web will tell you that this will happen. Possibly. (sigh!).

(The first beer from the prototype)

Have I improved the image of home brewing? Well, that is a question I will let others answer, I must be off for now as I have to dress for dinner!


--Peter Watson

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February 16, 2014  •  09:42 PM
Cudos Brother Watson. I was thorougholy entertained and educatated. Well written and interesting as I myself am somewhat of a tinkerer.
February 16, 2014  •  10:34 PM
Very nice. This would work great for carbonating a sweet cider without having to pasteurize.
February 16, 2014  •  11:16 PM
WOW, that is great!

I love tinkering with things, I am going to try this my self.
February 17, 2014  •  06:20 AM
Very nice write-up. Love seeing homebrewer create their own devices.

It appears you enoy this, which is most important, so this isn't meant to critisize. Oxygenation is definitely real, but I believe you don't experience it since you are only tapping 2 litres at a time. I'm betting it doesn't sit around long after exposure to the air.
February 17, 2014  •  09:46 AM
I love that
February 17, 2014  •  01:58 PM
I did not think CO2 tanks were to be used sideways?
February 17, 2014  •  04:34 PM
I'm no kind of kegging expert, but why not a pump tap? I mean you'd have to adapt it, but that seems ideal for what you're trying to accomplish--instant pressure.

Or--and this could be insane--something like the Magic Tap (as seen on TV). Man, those are only $10... they have a little AA-operated pump inside, from the look of things. Maybe I'll snatch one up for testing before they disappear.
February 17, 2014  •  05:57 PM
Kudos! It is not only effective but inexpensive and it looks great!
February 18, 2014  •  11:30 AM
great project! thanks for sharing!
February 18, 2014  •  11:06 PM
pondered on the same topic for many hours. best way to dispense from a 2L that is cheap enough to be worth doing. Store-brand soda comes in 3 liter bottles, check that out. I used an upside down rubber stopper stuffed into a drilled out soda cap, drilled the stopper with 5/32" gas in and liquid out. Cheers.
February 19, 2014  •  12:05 AM
Copper in contact with fermented beer isn't the best thing for your health but I like your creativity! Just change that diptube out to ss and rock and roll!
February 19, 2014  •  09:20 AM
I was unfamiliar with the term "singlet". A quick google image search turned up some things I unfortunately wont soon forget... and a scant few things i would like to remember. Excellent article and fantastic concept. I, on the other hand, have a problem keeping 5 gallon kegs full between friends and myself and swmbo. Perhaps I should consider myself lucky? ;) Great write-up though :mug:
February 19, 2014  •  12:33 PM
Hi Peter,
Some version of this is on my design list. One thing you should look at is a 20 oz paintball cylinder. They have to have paintball finatics down under.

What is the material used to pipe up your beer? If copper you may want to reconsider some other material. I have read the acidity in the beer leaches out something in the copper. Or you can just rename your beer Cooper's Copper.
February 19, 2014  •  02:39 PM
great writeup. currently researching for a soda making project and I think I can apply some of this.

If you want to revisit your bike pump three-hand setup, what homemade nerf gun guys do is use a bike pump to pump up a PVC cylinder that holds the pressure (like a super soaker or a compressor for pneumatic tools) and then bleed off that pressure as needed.
February 19, 2014  •  03:31 PM
there was a guy in binghamton or endicott ny back in the mid 90's that developed a system like this. the caps had two small diameter plastic ports, the gas in had a check valve on the inside. There was also cap that was meant to allow filling of a PET bottle with C02 from your C02 cylinder. was a pretty slick setup.
February 20, 2014  •  11:48 AM
Awesome article mate. You might be interested in the hacked "tap king" that are going around. I've modified mine to use a soda stream co2 bottle and have homebrew on tap in the fridge constantly. It isn't too hard and is a good fun mod without re-inventing the wheel. Also the bottles are 3.2 liters and you don't have to drink the whole thing as it's on co2. Anyway just a thought, hope your system is still going great guns.
February 20, 2014  •  06:58 PM
I was wondering what kind of fitting you have attached to the bottle cap. And can pick one up at my local hardware store?
February 20, 2014  •  08:42 PM
I'll echo others comments about the copper in contact with carbonated liquid

Copper in contact with carbonated liquid will poison you
February 21, 2014  •  04:36 AM
Thanks to all those who have voiced concerns about using copper tube in contact with carbonated beer. I have investigated this myself as far as I can using the internet and read various articles on the subject. I am not an expert nor a metallurgist so I will not offer an opinion either way,however I have replaced the tube with PVC. My advice to others would be to do your research and act accordingly.
February 22, 2014  •  05:36 PM
You can also bottle in 3 liter bottles (from the Dollar Tree) and dispense with a Coors Light Home Draft tap ($20 including 6 liters of 'beer'), or tap-a-draft ($35 for the tap). I sanitize 3, 6 liter bottles for a 5 gallon batch. I put corn sugar into two bottles and force carbonate the third so I can start drinking it the next day. But all are dispensed with CO2 (the tap has a built-in CO2 regulator and you buy the bulbs). The kegs last for months in the fridge.
February 23, 2014  •  02:29 PM
Youve done excactly the same principle as traditional keg draft dispenser will do! The keg is pressurized from co2 cylinder, then lifted up to draft arm via other tube from the keg!
February 23, 2014  •  02:35 PM
Here is my project to evaluate
February 27, 2014  •  07:57 PM
Can you please tell me more about the c02 tank and regulator you are using?
I have been searching hi and low for a small regualtor for my personal kegerator project also.

thanks !!
February 28, 2014  •  04:39 AM

Here is the link to the web site. Bunnings is an Aussie chain hardware store. The regulators fit the disposable bottles.


February 28, 2014  •  01:37 PM
Great read.. You had me laughing for a good minute when I read the part when the beer hit the ceiling. Great job working through the problems, you ended up with a great looking and easy way to dispense your drink. Cudos to you
March 6, 2014  •  08:47 AM
If you like this,have a look at the garden sprayer keg on Aussie home brew.
March 6, 2014  •  09:05 PM
Great read! I am impressed with your simplistic view, my views are similar. Due to your methods with PET bottles I will be bottling some soon.
I laughed so hard reading your first attempt... I was thinking of another way one could get co2 to just push beer and I thought of the aquarium method for increasing co2 levels for plants..., this link has a good video demonstrating a way to get co2, and I'm sure as homebrewers/inventors/atom splitters one of us could find a way to adapt this. Just a thought, and happy brewing
March 18, 2014  •  08:43 PM
What is the unit that screws onto the top of the bottle? Did you tap into the side for the air? Looks like a nice setup.
March 19, 2014  •  03:12 PM
@deeferdog When I worked for Coca-Cola Fountain in Atlanta, we had the same concerns. The parts that go into the field technician's trucks never include copper. The type of copper makes a difference and the duration has to be sufficient to dissolve enough of the copper to cause a problem. Your two litters at a time probably didn't harm you, but PVC is an improvement for piece of mind. My piece of mind; however, is shattered from the image of a middle aged smelly man in a singlet pouring home brew that I can't get out of my head. I am disturbed at the notion that maybe he is me.

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