DIY Carbonator




Just your typical electrical engineer with an addiction to space and the Cabinet Mountains Wilder...

This short instructable will show you how to make a carbonating tank. This is useful if you want to make your own soda, maybe you like fizzy coffee, or making fizzy fruit. The principle is simple. Water can absorb carbon dioxide (CO2) if they are both pressurized together. The colder the water (ice is not water, so not freezing temperatures) the more CO2 it will absorb. When the pressure is released the CO2 will start to escape from the water and creates a fizzing action just like your favorite bottle of root beer (it's Virgils...only try it if you're willing to be addicted).

Our DIY carbonator is going to be very simple. We just need a tank to store our carbonating target that is capable of being pressurized to about 100 PSI. Rich Faulhaber over at Evil Mad Scientist Labs was nice enough to share the idea of using a water filter housing. Check out to see how he did it. Follow on to the next steps to see my take on it.

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Step 1: The CO2 Tank

You can build all the carbonating vessels you want, but you can't carbonate anything without some CO2. Thanks to the popularity of paint ball, you can easily get a small CO2 tank and CO2. Just look up your local paint ball equipment supplier and buy a tank from them. The 20 oz tank I bought cost $25 and the "remote supply line" was $30.

The remote supply line makes this setup easy. One side screws onto the tank and the other usually has a quick connect system. I couldn't find fittings that would adapt the quick connect to the plumbing fittings on the water filter housing, so I just cut the paintball quick connect fastener off. With that out of the way, just use a barb fitting and a standard air compressor quick connect fitting to make things work with the water filter housing.

Be sure to use teflon tape on the threads of all connections to prevent leaks!

Step 2: The Pressure Vessel

The pressure vessel is the most expensive part of this build. There are many kinds of water filters; for refrigerators, water bottles, etc. The type you want is a "whole house" water filter. I bought mine from Lowes and it is a Whirlpool brand. I like the Whirlpool because they have a clear filter housing. There are many different sizes...the big one I bought holds two grapefruits and three oranges easily (after they are peeled). The down side is that it costs about $65.

Different filter housings have different connections, so this next part is going to be a bit vague. You need to find a way to plug one side of the filter housing and convert the other to the air compressor quick connect. For my filter housing it took the following fittings:

1 - 1" to 3/4" adapter
1 - 3/4" to 3/8" adapter
1 - 3/8" to 1/4" adapter
1 - air compressor quick connect recpticle
1 - 1" plug fitting

In the pictures you can see that I have some steel connectors and adapters, which is bad. You should only use brass fittings to prevent corrosion.

Another important addition to what you see in the pictures would be a pressure gauge. It would be easy to attach a pressure gauge to the plugged side of the water filter housing. Without the pressure gauge you don't know if you're over-pressurizing the housing, which is very dangerous. Be safe and get a pressure gauge!

Step 3: Using the Carbonator

Once you have it all put together, just put whatever you want to carbonate inside and then pressurize it with CO2. You can experiment with different CO2 pressures, different storage temperatures, and lengths of time it stays pressurized. In my tests with fruit I've found that you want at least 50 PSI and put it in the fridge for at least 1 hour. Once you open the pressure vessel you have about 30 minutes before the fruit isn't carbonated anymore.

If your pressure vessel is clear like mine you can see a lesson that every deep sea diver knows well. The bends, decompression sickness, divers' disease, caisson disease, whatever you want to call it, it's bad news. If you release the pressure from your system too fast the skin of your fruit will break open and bubbles will squirt out everywhere. The rapid release of pressure is more than the fruit can take. This is the same thing that happens to a diver's body if they surface from the bottom of the ocean too fast. The pressurized nitrogen in their body tries to escape any way it can, and that usually is through the blood vessels. Unlike a diver, your fruit will still be useful after suffering from the bends. It will just make a big mess inside the pressure vessel.

That's all there is to the DIY carbonator. I've filled my pressure vessel 5 times and still haven't ran out of CO2, so a 20 oz tank of CO2 can get you through lots of parties or curious children. Please be very careful when working with pressurized gasses and foods. Make sure your equipment is clean and free of oils, debris, metal shavings, and other harmful items. Use a pressure regulator or at least a pressure gauge to make sure you don't over-pressurize the water filter housing, 100 PSI is more than enough to carbonate anything this type of pressure vessel can handle. Be safe and have fun!

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    24 Discussions


    3 years ago

    its quite educative but i would like to try it first to see the efficacy. but this is quite amazing really . Thanks


    4 years ago on Step 3

    Actually, you really should use stainless steel fittings, not brass ones if there is any chance of carbonated liquids coming into contact with them. (CO2 reacts with liquids to create carbonic acid, which in turn dissolves the copper in brass, which will poison you.


    5 years ago

    Just curious, what does the fizzy fruit taste like?

    2 replies

    Reply 5 years ago on Introduction

    Adding CO2 to the fruit results in carbonic acids, which give most fruits a slightly tangy or bitter taste. The real effect is the fizz, like soda or pop rocks. The fruit tastes pretty much like itself aside from that.


    5 years ago on Introduction

    So if I mixed all the ingredients for root-beer (basically having just a flat soda), I could run it through this thing then bottle it?

    1 reply

    You could do, but the results would be mixed. This vessel takes a long time to open and that causes a lot of the carbonation to escape. This is great with fruit, because quick depressurization causes exploded fruit. It's not good for carbonating large amounts of liquid because the carbonation escapes out of the liquid before you can re-bottle it. Better to get a home brewer's keg and carbonating kit. It will probably cost you about the same in the end.


    8 years ago on Introduction

    Do *not* build or use this as shown, lest you find yourself with a face and eyes full of plastic shards. Google for "PVC compressed air", "hydrotesting tanks", or even "tire explosion" for more information and horror stories, but here's the short version:

    (1) You need a regulator between the tank and the filter housing. Putting a pressure gauge on there isn't enough -- pressure gauges can clog or stick, you can get distracted while pressurizing, and so on.

    (2) Always fill the filter housing to the top with liquid before pressurizing -- don't just drop fruit in it as shown. You need to get the air out. While that plastic water filter housing is fine for high pressure water, high pressure gas and plastic are a bad mix. Gas expands. Water doesn't. If the housing shatters when full of water, you get water all over the floor -- no big deal. But if the housing shatters when full of gas, the expanding gas will propel the pieces away from each other like shrapnel.

    4 replies
    Chris Loganstevegt

    Reply 7 years ago on Introduction

    First, the type of pneumatic gauge that is implemented here is extremely reliable and impossible to clog or stick.

    Second, if you fill the container with water, your fruit won't be carbonated. What a waste!

    Horror stories are just that. At 100psi, plastic isn't dangerous at all... A subpar vessel will crack and leak, rather than be blown apart. Things start getting unsafe at 500psi, because the type of failure is much faster. And be aware that unregulated CO2 is statically 850psi.

    Oddly, this exact setup as pictured is very safe because of the brass nipple with the pushed-on hose. That constitutes and engineered failure point that will pop off at a few hundred psi.

    Good advice (instead of a detrimental "horror story")... Always wear the proper personal protective equipment. In this case, gloves and safety glasses. And be aware of the specific dangers that your experiment poses.

    That's assuming you don't have a sudden failure mode, such as dropping the vessel.

    It's extremely risky advice to say that "plastic" isn't dangerous at 100psi. "Plastic" could mean any one of thousands of polymers, and that makes a huge difference. PVC, for example, sometimes fragments suddenly, rather than cracking and leaking. I've had a PVC spud gun valve fail at 100psi. Luckily I was standing well away and to the side when the two-pound plastic valve core launched itself clear through the back of the valve and across my friend's lawn, sending sharp frags everywhere.

    Is a 20 foot pneumatic cannon different than a water filter? Of course, and that's exactly my point. I agree that horror stories are, by themselves, not useful advice, but cavalier advice can be far more dangerous.

    The bottom line is pretty much unless you have data on what a particular system does when it's pushed past its limits, it's unpredictable, and you can't accurately assess the hazards, because you don't know them.


    7 years ago on Introduction

    It would certainly be prudent to check the pressure rating on the filter. It ought to be pressure rated, since it's designed for water lines. It's likely rated to 120-125 psi, but individual models differ, so you definitely want to know before you pressurize.

    It looks like the one on this page:

    If that's the case, it's rated to 125 psi (water pressure) and it's made of polypropylene, which does have the 'safer' failure mode of cracking and leaking, rather than fragmenting.

    In all likelihood, it's totally fine for this application, though there are technical differences between water max pressure rating and air max pressure rating, as stevegt pointed out.


    Reply 8 years ago on Step 3

    It adds carbonation to anything that you can fit inside and has some water content. For example, if you were going to make your own soda (some call it pop) you could use this to make it carbonated, or you could use it to re-carbonate soda that has gone flat.

    Well...there are two things going on with Guinness. They are using a CO2/nitrogen mix and a ping-pong ball like thing with a small hole in it. You could add CO2 and nitrogen using this DIY carbonater. Just pump in whatever amount of each you want and that's that. You'll probably notice that you don't get the foamy head that Guinness has when you pour out your beer, though. That's where the ping-pong ball comes in. During the pressurization the beer/nitrogen/CO2 mix is forced into the ping-pong ball through the tiny hole. Then when the can is opened the pressure in the ping-pong ball causes it all to squirt out and foam up.

    So, if you just want nitrogenated beer you're ready to go just swap CO2 for nitrogen. If you're looking for that signature foamy head you're going to have to experiment with ping-pong balls and how big of a hole to poke in it.