If your drinks keep coming out flat, foamy, or “not quite right,” the problem may not be your equipment, your lines, or even the product itself. The real issue could be your CO₂ – and you may not know it’s happening.
Many bars, breweries, and restaurants serve drinks that taste off or lose fizz too quickly, even though they’re using certified “beverage-grade” gas. The shocking truth is that beverage-grade doesn’t always mean clean. Your CO₂ can still contain trace contaminants that slip through the supply chain unnoticed.
These impurities (hydrogen sulphide, carbonyl sulphide, hydrocarbons, moisture) are invisible. You can’t see them in the cylinder. You won’t spot them during installation. But you will notice their effects.
They create chemical or sulphurous smells, weaken carbonation. and ruin foam stability. Contaminents leave drinks tasting dull, sharp, or strangely bitter. In many cases, they make your team chase the wrong solutions: adjusting pressure, deep-cleaning lines, swapping kegs, or replacing regulators. Without ever fixing the root cause.
Contaminated CO₂ is a hidden industry problem, and it damages both sensory quality and operational consistency. It leads to wasted product, higher costs, and more customer complaints. And because the contamination is invisible, it can go on for weeks before anyone connects the dots.
That’s why CO₂ must be cleaned before it reaches your drinks. When gas is purified, flavour improves, fizz lasts longer, and every pour becomes predictable.
What Is Carbon Dioxide Cleaning?
Carbon dioxide cleaning is one of the most important yet least understood parts of beverage quality control. Many teams think it refers to cleaning cylinders or rinsing lines, but CO₂ cleaning is very different. It means removing trace impurities from the gas itself before it ever reaches your drinks.
In the beverage industry, CO₂ cleaning protects flavour, aroma, carbonation, and foam stability. It ensures the gas entering your draught or production system is clean, stable, and neutral. Exactly as it should be.
The Meaning of CO₂ Cleaning in the Beverage Industry
CO₂ cleaning is the process of purifying carbon dioxide by removing contaminants that can affect drinks, including sulphur compounds, hydrocarbons, moisture, and chemical residues.
It is not:
- washing cylinders
- sanitising regulators
- flushing gas lines
It is:
- cleaning the gas itself, using advanced filtration or polishing technology that captures impurities at a molecular level.
This distinction is vital. Contamination almost always starts in the CO₂ supply, not the cylinder or the lines. If the gas is impure, it affects the drink no matter how clean the system is.
Why CO₂ Becomes Contaminated
CO₂ contamination can occur at any point before the gas reaches your venue or brewery. Even suppliers who meet required standards can unintentionally deliver gas containing trace impurities.
Common contamination sources include:
- Transport: CO₂ picks up moisture or particulates from tankers, pipes, or fittings.
- Storage: Long-term storage can introduce corrosion or environmental contaminants.
- Cylinder refilling: Residue or oil from previous fills can remain inside tanks.
- Production process: Impurities may form during CO₂ capture, compression, or purification.
The most common contaminants found in beverage CO₂ include:
- Hydrogen sulphide (H₂S): rotten egg or sulphur smell
- Carbonyl sulphide (COS): chemical or burnt aroma
- Hydrocarbons: solvent or plastic-like notes
- Moisture: affects carbonation stability and foam performance
- Oil traces: often introduced during cylinder handling or compression
Any one of these can distort the drink’s sensory profile.
Beverage-Grade CO₂ vs Truly Clean CO₂
Many operators believe “beverage-grade CO₂” guarantees purity. It doesn’t. Beverage-grade CO₂ only needs to meet minimum industry specifications set by ISBT and EIGA. These specifications still allow measurable levels of COS, H₂S, and hydrocarbons – levels small enough to pass testing, but large enough to affect taste and aroma in real conditions.
This is why drinks can taste strange even with compliant CO₂. “Beverage-grade” reflects what is allowed at the point of production, not what reaches your tap.
Truly clean CO₂ is gas that has been polished – filtered again at the point of use to remove the contaminants that slip through supply chains. This is what ensures a neutral, clean-tasting, fully carbonated drink.
The Hidden Contaminants Found in CO₂ – and Why They Matter
High grade CO₂ should be clean, neutral, and flavourless. But in reality, it often contains microscopic contaminants that dramatically change how drinks taste, smell, and behave. These compounds are invisible, yet their impact is immediate and unmistakable. Understanding them is key to understanding why CO₂ cleaning is essential.
Hydrogen Sulphide (H₂S)
Hydrogen sulphide is one of the most recognisable contaminants. Even in tiny amounts, it releases a sulphurous “rotten egg” smell. This odour overwhelms delicate aromas in beer, soft drinks, and carbonated water. Drinks that should taste crisp instead smell unpleasant and chemical.
Carbonyl Sulphide (COS)
Carbonyl sulphide introduces a sharp, burnt, or chemical aftertaste. COS is especially problematic because it is stable and difficult to remove without proper filtration. Even trace levels can linger in the final beverage, masking intended flavours and leaving a harsh finish.
Aromatic Hydrocarbons
Aromatic hydrocarbons create plastic-like, oily, or solvent-style flavours in drinks. These compounds often originate from CO₂ production, transport, or cylinder contamination. Their presence can make beverages taste artificial or “off,” even when all other parts of the system are perfectly maintained.
Moisture and Particulates
Moisture reduces carbonation stability and accelerates staling. It can also promote microbial growth inside dispense systems. Particulates (such as rust, dust, or oil droplets) interfere with pressure control, damage equipment, and disrupt how CO₂ dissolves in the drink.
Both moisture and particulates affect the physical quality of the pour as much as they affect flavour. They are among the most common causes of flat or inconsistent drinks.
How These Compounds Affect Drinks
Contaminants in CO₂ can disrupt every sensory and operational aspect of beverage dispense:
- Flatness: Impurities interfere with CO₂ absorption, reducing fizz and carbonation strength.
- Poor foam retention: Contaminants destabilise foam proteins, causing beer heads to collapse quickly.
- Bitter or chemical aroma: Off-odours become noticeable before the drink is even tasted.
- Reduced shelf life: Oxygen, moisture, and reactive gases accelerate oxidation and staling.
Even the smallest amount of contamination can ruin an entire batch, damage customer perception, and increase waste.
How Carbon Dioxide Cleaning Works
Carbon dioxide cleaning removes the impurities that damage flavour, aroma, carbonation, and consistency. The most effective method used in the beverage industry is CO₂ polishing – a multi-stage purification process that ensures gas is clean at the point of use, not just at the point of supply.
Multi-Stage CO₂ Polishing
CO₂ polishing uses several layers of specialist media to strip contaminants from the gas stream before it reaches your drinks. Each stage targets a different problem:
- Chemical impurities: compounds such as hydrogen sulphide, carbonyl sulphide, and aromatic hydrocarbons are absorbed or neutralised.
- Moisture: excess water vapour is removed to improve carbonation stability and prevent microbial growth.
- Oil traces: oil droplets introduced during compression or cylinder filling are captured before they reach the beverage system.
By cleaning CO₂ at this molecular level, polishing creates a neutral, stable gas that behaves exactly as it should – predictable, clean, and consistent.
Adsorption Technology
At the heart of CO₂ polishing is adsorption. This process uses specialist media that attract and hold impurities while allowing pure CO₂ to pass through. Two technologies dominate:
- Activated carbon: ideal for removing hydrocarbons, odours, and organic compounds.
- Molecular sieves: engineered to capture gas molecules such as COS and H₂S that standard filters cannot remove.
These materials trap contaminants securely, ensuring they never reach your product. Adsorption is far more precise than mechanical filtration, making it the preferred method for protecting beverage quality.
Why Polishing > Standard Filtration
Standard gas filters are designed to catch particles, not molecular impurities. They can remove rust, dust, or debris from cylinders but cannot stop the chemical contaminants that affect taste and aroma.
Polishing is different. It:
- Targets contaminants measured in parts per million.
- Removes sulphur compounds and hydrocarbons that alter flavour.
- Eliminates moisture that destabilises carbonation.
- Cleans the gas itself – not just the equipment around it.
This is why breweries, soft drink producers, and draught venues use polishing systems when consistency, quality, and flavour matter.
Flow Stability and Sensory Benefits
Clean, polished CO₂ behaves more predictably, improving every stage of beverage dispense. Operators immediately notice:
- Brighter flavour: no sulphur, chemical, or plastic-like notes.
- Longer-lasting fizz: carbonation stays stable from keg to glass.
- Consistent foam: beer head formation and retention improve dramatically.
Polished CO₂ ensures that what reaches the drinker is the product you intended to serve — clean, fresh, and full of character.
CO₂ Cleaning Technology Used in the Beverage Industry
Effective carbon dioxide cleaning relies on the right technology – systems designed to remove trace impurities before they reach your drinks. In the beverage sector, CO₂ polishing systems are now a crucial part of quality assurance.
Sure Purity’s Carboguard range leads the industry by delivering reliable, high-performance purification for both production and dispense environments.
Carboguard Mini
The Carboguard Mini is engineered for bars, restaurants, and fast-food chains where consistency at the tap is essential. These venues often experience flat or off-tasting drinks without realising the CO₂ is the cause.
Carboguard Mini removes:
- Carbonyl sulphide (COS)
- Hydrogen sulphide (H₂S)
- Aromatic hydrocarbons
- Moisture and trace oils
By polishing CO₂ at the point of use, it prevents the off-flavours, weak fizz, and chemical aromas that damage the guest experience. Drinks pour brighter, taste cleaner, and hold carbonation for longer – all from a compact system designed for busy dispense environments.
Carboguard Craft
For breweries, gas purity matters even more. CO₂ interacts with beer throughout production, from tank purging to carbonation. Any contamination at this stage influences aroma, foam, and stability across the entire batch.
Carboguard Craft is built for this environment. It offers high-capacity, multi-stage CO₂ polishing that protects carbonation quality throughout brewing operations. Breweries using Carboguard Craft see:
- More consistent carbonation levels
- Improved flavour stability
- Reduced risk of sulphur or chemical off-notes
- Fewer quality-control deviations
It supports both small craft producers and large-scale facilities that rely on precise carbonation control.
Snowstorm Filling & COS Barrier
Sure Purity’s systems use advanced media engineering to reach a higher level of purification. Two features set Carboguard apart:
- Snowstorm Filling: a unique process that packs the media with 12% more surface contact than traditional systems. More contact equals more contaminant removal.
- COS Barrier: a specialised filtration layer designed to capture carbonyl sulphide — one of the hardest contaminants to remove and one of the most damaging to flavour.
Together, these innovations deliver industry-leading purification performance, surpassing standard expectations for beverage CO₂.
Comparison With Parker PCO₂ Systems
Many beverage operators currently use Parker PCO₂ filters. While effective to a point, these systems have notable limitations. Carboguard offers several advantages:
- Longer filter life: annual replacement versus Parker’s typical six-month change cycle.
- Higher impurity removal rate: superior COS and H₂S capture through advanced media design.
- Lower OPEX and maintenance: fewer changeouts, reduced labour, and less downtime.
Carboguard systems are designed for demanding environments and provide measurable improvements in beverage quality, consistency, and long-term operational efficiency.
Signs Your Drinks Need CO₂ Cleaning
Most gas-related problems stay hidden until they show up in the glass. If your drinks keep losing fizz, tasting odd, or pouring inconsistently, the issue is often poor CO₂ quality. Here are the most common warning signs that your system needs CO₂ cleaning.
Flat or Foamy Pours
Flat drinks are one of the clearest signs of contaminated gas. Impurities interfere with how CO₂ dissolves into the beverage, causing weak carbonation and dull mouthfeel. Foamy pours can signal the same issue – poor-quality CO₂ disrupts pressure stability, creating turbulence as the drink leaves the tap.
If pressure adjustments don’t fix it, the gas supply is the likely culprit.
Sulphur, Plastic, or Chemical Smells
Off-aromas are strong indicators of sulphur or hydrocarbon contamination. Drinks may smell like:
- Rotten eggs (H₂S)
- Burnt matches (COS)
- Plastic or solvent (aromatic hydrocarbons)
These faults overpower natural flavours and instantly signal something is wrong.
Inconsistent Carbonation Levels
If two drinks from the same keg or syrup bag don’t taste the same, the gas supply is often to blame. Contaminated or unstable CO₂ creates unpredictable carbonation, even when pressure and temperature appear correct.
Shorter Shelf Life
Contaminants like moisture and oxygen accelerate oxidation. Beers stale faster. Soft drinks lose brightness. Carbonation drops long before the keg or BIB is empty.
If your stock isn’t lasting as long as it should, your CO₂ purity may be the reason.
Customer Complaints
Guests may report drinks tasting dull, sharp, chemical, or “not like they used to.” These complaints often appear in waves — a sign that something in the gas supply has changed.
A Real-World Example
One UK brewery struggled with recurring complaints about a burnt aroma in its pale ales. After weeks spent checking lines, regulators, and kegs, the issue was finally traced back to COS contamination in the CO₂ supply. Installing a Carboguard filter removed the impurity immediately, restoring flavour and stopping the complaints overnight.
When drinks behave unpredictably, CO₂ quality is usually the missing piece of the puzzle.
How We Can Help
Clean Carbon Dioxide is the foundation of drink quality. When the gas is pure, drinks stay bright, consistent, and full of fizz. When it isn’t, carbonation collapses, flavours dull, and customers notice. Most venues and breweries work hard to maintain lines, equipment, and temperature – yet overlook the one ingredient that affects every single beverage served.
Carbon dioxide cleaning removes the impurities that cause flat pours, chemical aromas, and unpredictable flavour changes. It protects carbonation, supports foam stability, and gives operators confidence that every drink will taste the way it should.
Sure Purity makes this process simple. Our Carboguard systems use industry-leading CO₂ polishing technology to remove sulphur compounds, hydrocarbons, moisture, and other trace contaminants before they reach your drinks. This protects flavour, extends shelf life, and stabilises carbonation across every serve.
If you want cleaner-tasting drinks, stronger fizz, and fewer customer complaints, the solution starts with your CO₂. Contact us today.
