I am an unabashed soda-holic. I wrote up a long article about my history and pursuit of better (and cheaper) soda in the home. This article is how you can skip ahead of the line, avoid being beholden to proprietary commerce (koff, koof, SodaStream, koff), and get the calibre of soda you want at less than $0.02 a litre*.
NB, this is a late draft of this article. I plan on updating it with photos and video; but I’m in a rush to get it out based on twitter demand!
First, a bit of history: Why is carbonated water often called “soda water”? Because before the efficient use of C02 gas in “charging” water to become carbonated, people could carbonate water by using sodium bicarbonate (baking soda) and some kind of acid (like citric acid); these two elements combined would release C02! (in the past, stuff like sulfuric acid and chalk were used to create bubbly water - dangerous stuff!). In this article, I really should be using “carbonated water” to describe what I’m writing about, but please excuse me if I call it soda water instead.
For decades now, bars and restaurants have offered soft drinks (sodas, pop, whatever you want to call it) in bulk by using two things - a canister full of concentrated syrups (from brand names like Coca Cola or Pepsi or Dr. Pepper), and pressurized tanks of carbon dioxide (Co2). Complex systems introducing ice cold water to the C02 through a regulated feed tube, and that newly created soda water would mix with preset amounts of the syrup to produce soft drinks on the fly, on demand. These systems aren’t practical for home use, because of the expense of the equipment used, the space they took up, and the need to high-chill water on demand. Why chilled water? The colder water is, the better C02 incorporates into the water. If you try to carbonate room temperature water, it will contain less than half the carbonation that 3C water will.
Enter the Carbonator Cap
In the mid 1990s, a fellow patented an invention that would turn the home carbonating game on its head, as far as water is concerned. That patent is for the carbonator cap. It’s entire purpose was to turn commonly used C02 tank / regulator rigs used for beer serving (a much simpler system than soft drink delivery systems) into a carbonation system for water, using standard 2l PET bottles (those high pressure plastic bottles all soft drinks are sold in). It’s taken a long time for this patented idea to become a product, but it started showing up in the late 1990s with limited production runs. Today, other similar devices have come out, including steel ones, but you can still buy the original Carbonator Cap. You can also build your own filling system using ball lock filling caps and tire inflation valves (though they can make everything smell like rubber).
This cap, along with a standard draft keg tank system (consisting of a C02 tank, any size from 2lb to 30lb or bigger (price is $5-$35 to refill, + deposit, between $20 and $100 on the actual tank), a draft keg pressure regulator (usually under $50) and a line and ball lock filling cap (usually under $15), is all you need to start making soda at home, at any strength of bubbles you want. You should be able to find most of these things at any home-brew beer store as well. And of course, you also need some some empty PET soda bottles, 500ml to 2l in sizes.
I have this system, based around a 30lb tank. My initial investment was about $150 ($190 Cdn dollars), plus a $30 payment for the first tank of gas (though I will get $100 CAD back once I return the tank and not get another refill - as if that will happen lol!). That 30lb tank lasts me at least one full year, even when making up to 6l of soda per day (my current average is 2.5 2l PET bottles consumed a day).
Let’s Look at the Math
Before I get into how to use the above-described system in your home, let’s look at the current ways to get soda water in your home and how much they cost — and I provide a percentage comparison to a home keg C02 system.
Buying Pre-made Club Soda: Here in Vancouver, Canada, a 2l bottle of club soda costs $1.50 plus deposit, on average. Sometimes as much as $2.50, sometimes as little as $0.99. If I went through 2.5 bottles per day, that would be $3.75 per day, or $1,370 per year. If you buy cans, it’s even higher.
This option is 4,450% higher in cost than a home keg system.
Using SodaStream: I do not recommend SodaStream (that company still owes me $300, long story, covered in my other soda water article). And it doesn’t carbonate as strongly as a home C02 tank system does — SodaStream maxes out at around 20psi of pressure. And while SodaStream is marketed as cheap, it isn’t that cheap. Currently in Canada, a tank refill, not including deposit, is $20 for a tank that can barely carbonate 50l of water (they claim 60, but that’s if you can accept very tepid carbonation). You cannot buy the 120l tanks in Canada, so we’re limited to the small paintball gun sized tanks. Here’s the cost breakdown, and I’m being generous here, basing it on the “3 squirts of pressure” they recommend: $0.40 per litre, or in my 5l/day consumption, $2/day, or $730 per year.
This option is 2300% higher in cost than home keg setup.
Using Siphon Bottles: I love siphon bottles and have a collection of them, vintage and new. But they have three big problems. First they provide even less carbonation than SodaStream does. Second, the cartridges used aren’t cheap. Even ifyou buy Co2 cartridges (needed for the siphon to do its thing) in bulk, you can get them for about $0.35 per. but you’ll have to buy over 500 of them to get anything near this price. And third, there’s a lot of waste to deal with - all that metal in the one-time use cartridges; if you can find a place to recycle them, it’s a pain to collect and transport them. Also, siphon bottles typically can hold up to a litre of cold water, but again, if you carbonate a full litre with just one cartridge, it will be extremely weak carbonation; so as a result, I was only carbonating about 750ml of water. In my consumption, I’d use up to 5 cartridges a day costing $1.75, delivering less than 4l of carbonated water. Per year that is $640 roughly.
This option is 2000% higher than a home keg setup.
Using A Home Keg Co2 System: After an initial $100-$200 investment in parts (a big part of this is a deposit on a tank you can get back), You’ll be paying between $5 and $35 to refill the tank with C02. I pay $30CAD to refill a 30lb tank. That 30lb tank lasts me at least 12 months (my first tank lasted 14, my second about 12); At 5l per day, that’s 1825l a year. That’s a cost of $0.0165 per litre. My daily cost? $0.08. Yearly? Aforementioned $30.
* For all sensible purposes, you’re getting soda water for nearly free, but let’s look at it another way - amortize the entire cost (incl. deposit) over that first year. I paid $195 for my rig setup and $30 for the first full C02 tank, $225. That works out to $0.12 per litre produced, or in my case, $0.60 per day for the first year. If you use this math on a SodaStream system, your cost is more like $0.55 per litre, $2.75 a day, and $1,000 for the first year. For the home carbonator setup, once you get into year 2 and beyond you’re getting soda water for less than $0.02 a litre, where the SodaStream is still $0.40 a litre, or a 2300% increase in cost!
Becoming a Home Carbonated Water Manufacturer
So you bought (or leased, or borrowed, with deposit) a nice C02 tank. It could be a mega-sized paintball gun tank (some people claim they can get the tanks refilled for free at paintball gun places!), a 5lb, 10lb, 20lb, 30lb, or even 50lb tank. Full, it holds C02 at 900psi or higher. Because your PET bottle would explode at that pressure, you also bought a keg system regulator for the tank, one that allows you to dial up or down the pressure you fill your bottles at (these usually will regulate the pressure down, delivering 5psi to 60psi which you can adjust). You bought a simple pressurized line and ball-lock filling cap used for home and mobile beer keg systems. You bought a Carbonator Cap. And you bought your last half dozen (or so) Club Soda 2l bottles (at least for the next six months!). Here’s how it all works together:
First, you fill a 2l PET plastic bottle with water, leaving about 7–8cm of headspace (just fill water until the bottle starts curving towards its top). Why the headspace? You need to have enough surface space for the C02 to saturate into your water. Next, make sure the bottles are chilled. We leave at least 2 filled bottles in the fridge overnight to get to around 3C (35–38F).
Once you’re ready with cold water in your PET bottles, here’s the next steps:
- take the bottle, attach the carbonator cap to the bottle, squeezing out all the air in the PET bottle before making the cap air tight.
- Check your Co2 rig, you want the regulator to be set at around 35–55psi (depending how strong you want the fizz — start at 35psi and adjust after sampling your beverage).
- Make sure your Co2’s tank main valve is off, and your safety release lever on the regulator is in the off position
- Attach the ball lock cap to the carbonator cap. Some residual Co2 will make its way into the bottle, but it won’t be full, or pressurized yet.
- Unscrew the tank’s main pressure valve to open, then slowly move the regulator’s safety release lever to the on position to fill and pressurize your PET bottle of water (key word: slowly).
- Once the PET bottle is filled with pressurized Co2, start shaking the bottle rapidly. C02 will only dissolve into water it is actually touching; if you don’t shake the bottle, it will take an hour to fully dissolve into water; shaking rapidly will constantly expose new water to the Co2 “gas”, speeding up the Co2’s incorporation into the H20.
- Shake the bottle for about 20–30 seconds. If you listen carefully, at some point, you’ll stop hearing the “hiss” of the pressurized C02 moving from the tank to the PET bottle — at this point, your water is nearly fully saturated with all the C02 it can handle — but not quite. There’s still some oxygen and other elements of “air” in there.
- Optionally, you can do a second C02 introduction; flip the regulator valve’s safety latch to off, and remove the ball cap from the carbonator cap on your bottle. Slowly unscrew the carbonator cap, and you’ll release all the pressure in the PET bottle (careful, it will bubble up and can spray you if you do it too fast). Let the bubbles settle for 10 seconds, then put the Carbonator cap back on, squeezing the bottle again to remove all (most) of the air inside as you tighten it. The bottle will continue to fill with gas (C02 at this point) once the cap is on securely. Reattach the ball lock cap from your tank, and flip the safety lever on the regulator back to “on” to re-pressurize the PET bottle. Shake like crazy again for 5–10 seconds. All of this optional secondary amount will remove remaining oxygen etc from the bottle and just keep it a full h20/c02 environment, making the water even more fizzy.
I don’t really do step 8 any longer. It doesn’t make that much a difference to the final fizz. And besides, leaving the filled PET bottle, uncapped, in the fridge before turning it into soda water helps evacuate residual oxygen anyways. But there you go — that’s the full steps to making soda water at home from a commercial Co2 tank.
PET Bottles are built to withstand well over 125psi (failure rate is rated at 150psi), and they are a wonder of modern engineering, but they do not last forever. Count on replacing yours every 250–500 uses. (sidenote: isn’t it amazing this product people normally use once and dispose of / recycle has such a long lifespan of usefulness?) You can prolong the life of your PET bottles by controlling how fast you pressurize them: don’t just jam the regulator’s safety lever open, but slowly do it. Ditto with releasing pressure. I’ve used bottles for as long as 500 refills, but I get a bit nervous by that point. The super safe will replace bottles every six months or so (but I’ve heard of people using the same PET bottles for years). If they fail, the worst that can happen is you’ll get a high pressurized soak of ice cold water.
Tanks are big and ugly, so keeping one in the middle of your kitchen might turn off some people. You should keep it in a cool, dark place, never in sunlight. We live in a condo, so ours is kept on the deck, but in full shade; if it gets above 25c in the summer, I bring it inside just as precaution, and keep it in the closet. It rarely gets below freezing here in Vancouver, so I don’t know if you should bring it inside if it gets below 0C - I always try to be safe, so I would.
Make sure your regulator is 100% working and attached - you are dealing with something with incredibly high pressure (the C02 tank holds the gas at up to 900psi!!! and this can be explosive). If you’ve never done this before, find a friendly, hands on beer brewing place and ask them to show you the ropes, set up your tank properly, and check the connections and fittings. That in mind, all my advice above and below is at you own risk.
Keep your main tank valve off when not filling your PET bottles. This serves two purposes: first it’s an extra safety precaution to keep your Co2 tank safe and sealed, and second, it prevents any gas leaks through the regulator system when you’re not filling bottles. Even the best regulators can lead a bit of gas (think a dripping faucet effect); a slight leak could empty your tank over a period of days or weeks.
It’s not just for water! That’s right, you can carbonate almost any liquid with your new system. Just keep this in mind: sugar = foam and bubbles = a huge mess. You can avoid huge bubbles and a mess by being patient - do the carbonating thing (including shaking the bottle), but then set it aside for up to 10 minutes or more. When you go to finally unscrew the carbonator cap, do it slowly and methodically in stages. I’ve carbonated wine, re-carbonated beer (awesome use btw, if you buy beer in growler bottles!), even carbonated mixed cocktails like negronis (mmmmm tasty!).
Become Your Own Fancy Mineral Water Manufacturer!
About 75% of the time I make my home is a homemade version of the famed natural Seltzer Waters of Germany, which don’t have any major minerals of note. So I guess I could say I am a Seltzer Water Manufacturer. But I also make my own version of Club Soda. What is Club Soda? In short, it’s an artificial version of waters like Perrier or Gerolsteiner,
What I’m trying to say is, mineral water is just carbonated water with added minerals. There’s so many minerals to choose from, including things like sodium or potassium bicarbonate, potassium citrate, sodium citrate, sodium chloride or calcium chloride just to name a few (none of these things are bad, in fact, they are all good for you — the sodium citrate for example helps make your urine less acidic and improves your kidney’s ability to process things; as far as the typical sodium overall in 500ml of Club Soda made at home, it is under 50 milligrams). If you’re a true super geek, go to this link, read this article, and download the calculator to clone the world’s famed mineral waters.
I’ve done a lot of experimenting with various minerals and salts, and have come up with a recipe I love the taste of. Call this Prince Waters. To my two litre PET bottles, I add the following:
- 1/8tsp baking soda,
- 1/8tsp potassium sulfate,
- 1/16tsp sodium citrate,
- 1/16tsp calcium chloride.
I know these measurements are hard to eyeball; I did it by weights originally (I have 1/100th gram scale), but have lost the numbers - I now just eyeball them based on what they weighed out too. All of this turns the beverage into water with a slight sharp bite (not acidic at all).
Make Your Own Soft Drinks!
The beauty of being your own seltzer water manufacturer is you can also be your own soft drink maker, making them at any strength or sweetness you desire! You can buy concentrated syrups all over the place: even Ikea has some — their lingonberry syrup and elderberry syrups work great in making home soft drinks. If you visit Italian delis and grocery stores, you’ll probably find shelves full of concentrated fruit syrups (blood orange, mmmm!) that are commonly used in making Italian Sodas.
I’ve tried everything from the syrups in cocktail cherry bottles, to making my own sweet ginger syrup for home made ginger ale (follow this recipe, skipping the yeast and fermentation part). I know one person who just likes adding a teaspoon of table sugar to his 2l bottles (slowly, be careful of the fizz!), and lets it slowly dissolve.
Probably my favourite type is making a home made version of Orangina. I actually don’t make this often since I need to avoid the acid in orange juice) but about once or twice a month, I gear up for it as a treat. Here’s how I do it: buy 1 can of frozen concentrated orange juice (I get the low acid variant), and keep it in the fridge, so it’s liquid. When I pour myself 300–500ml of soda water, I can add a teaspoon or two of the concentrated OJ to the glass, then add a a squeeze of lime, and stir gently. The result is similar to Orangina (which is 12% fruit juice, and 88% sweetened carbonated water); except mine is not as sweet and probably a lot more healthy.