Cheaper Sodastreaming with bulk CO2

We like our bubbly water, and although you can get fridges that carbonate… they are horrendously expensive. The next best thing is a sodastream machine, but again… this can be a huge ongoing cost if you stick to the sodastream brand cartridges.

We started with their 60L gas cylinders, (there were 30L ones around but sodastream have phased them out). The 60L means that they should carbonate about 60L of water, but they actually has about 400g of CO₂ in them. As at early 2023, I can buy off the shelf a 60L canister for around $40 (link here, but who knows how long this link to Briscoes will work….) These aren’t new cylinders, but you don’t need to swap one. Or you can swap an empty one, and the cheapest ‘on special’ price I’ve ever paid for a refill is $20, but more realistically places like The Warehouse sell refills for around $27 (link to The Warehouse, as at April 2023).

There is another company recently pushing themselves called “Oh Bubbles“, that tout themselves as being “sodastream compatible”.  My most recent check shows that a one off refill is $28.50, but you can pay less for more refills, and it looks like they do a “yearly plan”.  I seriously doubt it is anywhere close to the DIY, bulk CO₂ options.

At a cost of $27, and using a 1 litre sodastream water bottle which holds around 850mL of water means that using their system costs about 38c to carbonate one litre (note that all prices here are in $NZ).

I did a quick extrapolation exercise (see above) and you can see how much buying the Sodastream refills is (even at the cheapest refill price), which is obviously the most expensive method. Buying a bottle has a payback somewhere between 20 and 30 standard sodastream refills… and less at a standard retail sodastream bottle price. After that refills from your local CO₂ supplier are all upside.

So, what options are there?

First you need your own bulk CO₂ storage

Well, for a cheaper alternative options, you are really going to need to get a CO₂ gas bottle of your own. You can easily buy them, and they come in 3kg, 5kg, 6kg and even larger. Essentially this what is what a CO₂ fire extinguisher is, so if you can get a used one of those or know someone in the fire industry, ask them. Otherwise look online for gas bottle sellers, or your local industrial gas place.

I found quotes for new 5kg bottles for around $275 and 3kg ones a little bit less (for example, from NZs auction site TradeMe). There are often cheaper 2nd hand ones available too, but I wasn’t keen to buy used. Make sure they are either empty, or designed for food grade CO₂ (they will say for brewing, hospitality or fish tanks etc)

However, I also found a “Swappa bottle” system, and although slightly more overall this works out to be a great option. Eziswap is a nationwide industrial gas supplier that swaps bottles, and I found a local agent near me (Shout-out to Pacificool, East Auckland). With a swap setup, you need to buy the first bottle from them and a 3kg one cost me $265. I could have gone up to 6 or 7.5kg for more and this would have saved more money longer term, but the upfront costs weren’t really worth it for me (not to mention the hassle of a heavier/bulkier bottle)

Before you buy a bottle… see the notes about siphon tubes near the end of the page.

How much is gas for a bulk refill?

Well my supplier charges $60 for the 3kg refill in my swappa bottle (food grade CO₂). Ignoring the upfront bottle cost, that is ( $60 / ( (3L/0.4L) x $27) ) or around 30% the sodastream refill price. You could of course go cheaper with a bigger bottle and maybe it is slightly cheaper to fill your own bottle at other suppliers.

How do you start cheaper bubbling?

Note that ANY adaptor you get that fits into the sodastream, ensure it is made for the NZ/AU machines. The threads are different for different parts of the world, presumably as another commercial control by sodastream. Some dodgy local suppliers do indeed sell the wrong ones, and I have had to invoke fair trading arguments to get a refund for one adaptor I bought online that was shipped from overseas.

Option 1: Refill the 60L sodastream cylinders from the bigger bottle

This was my first plan. It meant that I didn’t need a spaced for the 3kg bottle in the house and I could use the refills on 2 sodastream machines (we have one in the basement kitchen as well as upstairs). There was plenty of conflicting information online about this, and long story short… it was frustrating and a waste of time.

I’m not linking to the actual product but I bought a ‘Soda Stream Cylinder Filling Adaptor with Bleed Valve’ bought from a local brewing supplier. Plenty of people sell them and they are around $20.

However, the way newer sodastream bottles are made they have a one way fill set up that is almost impossible to get around without making some hardware modifications to the bottle (of course, they don’t want you to refill them). A few times I got the fill setup just right to get some flow into the bottle, but usually it would just lock up the valve and stop filling. I wasted a lot of gas bleeding them too, or letting gas escape.

I eventually did start work on modifying a valve but looked for better option in the mean time. There are other ‘filler hose’ options, and some may work better if you can release the CO₂ much slower. I suspect all methods used to work well, but sodastream have done a lot of work to perfect their ‘anti-tamper’ valve setup.

Option 2: Refilling paintball gun style canisters

You can buy an adapter to use paintball gun canisters commonly called the ‘Sodamod’. Airsoft canisters come in various sizes – I have seen them that hold between 70g and 700g of CO2, and this is a common mod to attach to a sodastream (if it will fit) Here is the link to the NZ/AU sodamod adaptor direct from the supplier, but bear in mind that I haven’t tried this setup and am only going by what I read online.

I assume most people get their refills from the airsoft gun people or a local sporting goods store, I know you can refill them yourself too with the right adaptors. This might be a good option for you dependant on price (and this might help if you want more than one, replaceable cylinder), but a quick look around shows me that a local store does 16oz (a bit bigger than a standard Sodastream bottle) refills for $16 (screenshot above in case the price changes) which is still not as cheap as other solutions. Remember also you you still need to price in the canister(s) again plus the (not inexpensive) sodamod adaptor.

Option 3: Direct connect

All’s well that ends well and this is the setup I went with. I bought a direct connection hose, branded as “FreedomOne Sodastream Adapter Hose MKII – 72inch” . I got the longer one of the two that I saw (there is a shorter 36 inch), as this enables me to place the cylinder on the ground and attach it to the sodastream machine on the bench. The hose wasn’t easy to find in stock, but a number of online local brewing companies list it on their websites (many out of stock). The place I bought it doesn’t seem to list it anymore, but it was around $120 shipped.

The advantage is that it is just connect-and-leave and gives me 7 or 8 sodastream cylinders worth of storage (around 450L of bubbly water). When I’m near to needing a refill, I just email the swap place and they make sure they have one in stock ready.

It does however mean that you need to have a large gas bottle in your kitchen or other place that holds the sodastream machine. Also, the hose comes out the bottom of the machine (so you could modify your bench and place the bottle in a cupboard maybe?) or I have just temporarily left the back off my machine as it has a removeable rear (not all of them do) and it is sitting out of the way on the floor.

My next plan is to place the large bottle in a covered space outside and run the hose though the wall – I have a perfect location to do this, but not every house would. I will modify the back cover of the machine too for hose entry.

A note about siphon tubes

Originally I got a bottle with a “dip” or siphon tube. This is a small tube that goes from the top (filler) to the bottom, so that when you open the valve, liquid CO2 is released rather than gas. If you are filling other bottles (eg filling sodastream cylinders) you can either get a bottle with this siphon OR you can just use the bottle upside down when filling (some people make themselves a handy filling stand).

Of course if you use my final method and just plumb it in, you can just use a standard (no siphon) bottle with no need to invert.

Summary

My hose setup works well and I highly recommend it. Having a bottle of CO₂ is pretty safe, but obviously ‘do your own safety research’, keep it away from heat and watch for leaks. If you end up refilling smaller bottles, look online for advice including such things as wearing gloves and having decent ventilation and/or extraction.

I personally suggest you don’t bother with the refill method, or if you do be prepared to drill out valves or be endlessly frustrated each time you try a refill. It is however nice to have bubbly water that never seems to end, at just over 10c a bottle. Yes, of course though… still (tap) water is still cheaper.