On an average workday in my home office/kitchen/lab, I make and drink 5 or 6 liters of seltzer, easy. True, I am a naturally thirsty person, but part of the reason I go through so much fizz is because—the way I make it— it’s so easy and after the initial investment, it’s practically free.
With home seltzer machines, on the other hand, the costs add up. The gas canisters for our winning SodaStream cost $15 for a refill; they’re advertised to make 60 liters of seltzer, but in practice, especially if you like your seltzer extra-fizzy like I do, they can’t make more than 40. If I used that setup, I’d be shelling out $15 every week to feed my habit.
Instead, for years now, I’ve been operating a simple DIY setup that’s paid for itself many times over. A carbon dioxide tank lives in a cabinet and connects with a flexible hose to any standard soda bottle. Refilling the tank costs about $20—but a single tank is enough to carbonate well over 500 liters.
Here’s how it works.
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What You’ll Need
A Carbon Dioxide Tank
This is the main investment in the system. A new tank costs $75-$125 on Amazon, eBay, or other retailers, in either the 5-pound or 10-pound size (which refers to how much CO2 it contains). True aficionados may want a 20-pound tank. It should have the standard CGA320 valve. After you own the tank, you can get it filled (or swap it for a full one) at a brewing- or welding-supply store.
A Double-Gauge Regulator
This component connects to the CO2 tank (via that CGA320 valve) and allows you to set the gas pressure. It has two gauges (hence the name): one of them shows the pressure setting in PSI, which is adjustable with a knob; the other one shows how much gas is left in the tank. The outlet of the regulator is a ridged hose barb, which connects to a hose, such as the one on your ball lock connector.
A Ball Lock Connector
This component includes a hose and clamp to attach to the barb of the regulator. It locks onto your seltzer bottles to dispense gas as needed.
A Carbonation Cap
Finally, this clever invention screws onto any standard 20-ounce, 1-liter, or 2-liter soda bottle. When it’s on the bottle, its valve connects to the ball lock connector, allowing carbon dioxide to flow into the bottle. There are plastic and metal carbonator caps available, but the metal ones tend to chew up the ball lock connector after a while.
How to Put Your Soda Maker Together
- Take the carbon dioxide tank to a local supplier, such as Airgas, and get beverage-grade carbon dioxide. Also ask for a nylon washer, which fits between the regulator and the tank to ensure a leakproof fit.
- Connect the ball lock connector to the regulator with the hose and hose clamp.
- Use a wrench to snugly connect the regulator to the carbon dioxide tank, including that washer where they fit together.
- Open the screw valve on top of the tank. The regulator gauges should spring to life, showing that the tank is full of gas. Use the knob on the regulator to adjust the PSI to 30. You may fine-tune it later to suit your fizziness preference.
How to Make Soda
- You need a clean standard PET plastic soda bottle, filled a little over ¾ full with cold water. You can keep filled bottles in the fridge, or put a little water in a bottle and freeze it and then fill it from the tap when you’re ready to carbonate it.
- Squeeze the bottle to empty out the air from the top, then tightly screw on the carbonation cap. You should have a somewhat squished bottle with no air in it.
- Press the opening of the ball lock connector onto the carbonator cap. It may require some force, especially when the cap is new. You’ll know it’s working because the bottle will suddenly inflate. Holding it upright, shake the bottle vigorously a dozen times. It should feel quite firm from the internal pressure.
- Pull up on the ring of the ball lock connector to release the connector.
Now you have a bottle of seltzer! Unscrew the cap, pour, and enjoy.
The bottles can be reused again and again, until they start to show signs of wear.
What Else Can You Carbonate?
Any transparent liquid works pretty well—apple juice, wine, cocktails. A cloudy liquid will turn into a frothy mess, because all the cloudy particles serve as nucleation sites for bubbles.