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CO₂

Refrigerator Zone CO2 PSI Carbonator Keg Gas H₂O Out

Swipe sideways to see the whole diagram.

Gas Path
Check Valve

This section covers preparing the keg, connecting the CO₂ system, and setting up dispensing.

Choosing Your CO₂ Tank

Section titled “Choosing Your CO₂ Tank”

Before you begin setup, you’ll need to choose a CO₂ tank size. Here’s a comparison to help you decide:

CO₂ Tank Comparison

Choose the right tank size for your needs and usage patterns.

Feature SodaStream Tank5 lb Tank10 lb Tank20 lb Tank
Capacity 60L (14.5 oz)~320L~640L~1280L
Initial Cost $30-40$60-80 (+ tank)$80-120 (+ tank)$100-150 (+ tank)
Refill Cost $15-20 exchange$15-25 refill$20-35 refill$25-45 refill
Refill Frequency Every 2-4 weeksEvery 2-4 monthsEvery 4-8 monthsEvery 6-12 months
Portability High Medium Low Low
Best For Beginners, small spaces, light useMost home users, moderate consumptionHeavy users, families, stationary setupsHeavy users, permanent installations
SodaStream Tank 60L (14.5 oz)
Initial: $30-40
Refill: $15-20 exchange
Frequency: Every 2-4 weeks
Portability: High
✅ Pros:
  • Easy to find exchanges
  • Compact size
  • No special adapters for standard use
❌ Cons:
  • Higher cost per liter
  • Requires TR21-4 adapter for keg use
  • Frequent exchanges

Best for: Beginners, small spaces, light use

5 lb Tank ~320L
Initial: $60-80 (+ tank)
Refill: $15-25 refill
Frequency: Every 2-4 months
Portability: Medium
✅ Pros:
  • Good balance of size/capacity
  • Standard regulator fits
  • Easy to transport for refills
❌ Cons:
  • Need to find a gas supplier
  • Takes up fridge space if inside

Best for: Most home users, moderate consumption

10 lb Tank ~640L
Initial: $80-120 (+ tank)
Refill: $20-35 refill
Frequency: Every 4-8 months
Portability: Low
✅ Pros:
  • Fewer refill trips
  • Lower cost per liter
  • Can stay outside fridge
❌ Cons:
  • Heavy (~25 lbs full)
  • Harder to transport
  • Takes more space

Best for: Heavy users, families, stationary setups

20 lb Tank ~1280L
Initial: $100-150 (+ tank)
Refill: $25-45 refill
Frequency: Every 6-12 months
Portability: Low
✅ Pros:
  • Best cost per liter
  • Rarely need refills
  • Commercial-grade reliability
❌ Cons:
  • Very heavy (~50 lbs full)
  • Must stay outside fridge
  • Harder to exchange

Best for: Heavy users, permanent installations

Step 1: Prepare the Keg

Section titled “Step 1: Prepare the Keg”
  1. Clean the Keg. Ensure the keg is clean and sanitized. See Best Practices for detailed cleaning instructions.
  2. Attach the Soda Carbonator Lid to the keg as per instructions.
  3. Ensure the keg is empty and the lid is sealed securely.

Step 2: Set Up the CO₂ System

Section titled “Step 2: Set Up the CO₂ System”
  1. Use food-grade tubing to connect the CO₂ regulator to a one-way check valve. Arrow should face the keg. You want to prevent water flow back toward the CO₂ tank, especially for when you swap tanks. For information on tubing sizes, see the Water Line Setup guide.
  2. Use tubing to connect the check valve to the gas quick-disconnect fitting.
  3. Attach the gas quick-disconnect to the gas post on the keg. Press hard until it clicks.
  4. Attach the CO₂ regulator to your CO₂ tank.
  5. Set CO₂ regulator to about 40 PSI
  6. Vent out all the oxygen by pulling the vent pin on the keg lid. Let the CO₂ fill the keg and vent a few times until only CO₂ remains. This prevents oxidation of trace elements in the water. Stop venting when water comes out, you’re just trying to vent air.
Why purge the air?

Oxygen left in the keg oxidizes trace compounds in the water and produces stale, cardboard-like flavors. It also leaves less room for dissolved CO₂, so the water goes flat sooner. Nitrogen in air is mostly inert, but it still takes space that CO₂ would otherwise fill. Purging until the gas coming out is CO₂ avoids both problems.

Carbonic acid (CO₂ + H₂O → H₂CO₃) is the mild acid in every sparkling drink. For most people it is a taste and a bit of fizz, not a health issue. People with sensitive stomachs sometimes feel bloated. It is much gentler on teeth than soda with sugar or citric acid.

Step 3: Fill and Carbonate

Section titled “Step 3: Fill and Carbonate”
  1. Open the refrigerator line and allow the water to fill the keg. Eventually it will stop filling.
  2. If needed, vent any remaining air by pulling the vent pin. Stop if water comes out.

Step 4: Set Up Dispensing

Section titled “Step 4: Set Up Dispensing”
  1. Connect tubing to a liquid quick disconnect and attach it to a valve.
  2. Connect another tube between valve and the tap faucet.
  3. Attach the liquid quick-disconnect to the liquid post on the keg. Press hard until it clicks
  4. Dispense some water to ensure the water system is working. It probably won’t be sparkling yet

Step 5: Wait for Carbonation

Section titled “Step 5: Wait for Carbonation”
  • It can take some time for the CO₂ to dissolve in a full keg
  • If the water is colder, it will carbonate faster.
  • Be patient - the first carbonation cycle may take several hours

Cold water holds more CO₂ and takes it on faster. Keep the keg at 35–40°F (2–4°C). 40 PSI is the pressure this guide uses. Higher is fizzier, lower is softer. The reference table shows the range.

If the water stays flat or a fitting leaks, use the troubleshooting checks.

Next Steps

Section titled “Next Steps”

House the keg in the fridge next. Then read Safety and pour the first glass.