It starts with a returned pint.
The customer leans over the bar, eyebrows raised. “This doesn’t taste right.” The bartender takes a sip, frowns, and nods. Another pint poured down the drain. Another dent in your margins—and possibly your reputation.
Every venue serving draught beer knows this moment. And often, it’s not the beer’s brand, the tap, or even the bartender at fault. It’s freshness.
Just like milk or bread, draught beer has a shelf life. But unlike other perishables, it’s harder to see when things start going wrong—until someone drinks it.
The question is: how long does draught beer really last once it’s tapped? And what shortens—or extends—that life?
In this guide, we’ll uncover:
- What affects draught beer shelf life behind the scenes
- How different beers last different lengths of time
- Warning signs of beer gone bad
- How gas purity and equipment setup directly impact beer quality
- Smart tips to make beer last longer without compromising taste
Whether you run a busy pub, a brewery taproom, or manage keg systems in a venue, these insights will help you protect quality, reduce waste, and serve every pint the way it was meant to be enjoyed.
What Affects the Shelf Life of Draught Beer?
Draught beer doesn’t have a one-size-fits-all expiry date. How long it stays fresh depends on several key factors that influence flavour, carbonation, and microbial growth.
Type of Beer
Pasteurised beers, commonly found in large-scale commercial breweries, last longer—typically up to 90 days after tapping. Unpasteurised beers (often used by craft breweries) have a shorter life, around 30–45 days. Cask-conditioned ales, which undergo secondary fermentation in the barrel, can spoil in as little as 3–7 days. Unfiltered beers also have more active yeast and proteins, which can speed up spoilage if not stored correctly.
Gas Type Used
The gas pushing beer from keg to tap matters. Using pure CO₂ helps preserve carbonation and taste. Mixed gas (CO₂/Nitrogen blends) is often used for specific beer styles like stouts, but ratios must be carefully managed. Using compressed air—a method sometimes seen in non-commercial settings—introduces oxygen, which accelerates oxidation and bacterial growth, rapidly reducing beer freshness.
Keg Storage Temperature
Temperature fluctuations affect beer stability. Kegs should be stored between 11–13°C in a properly ventilated cellar. Too warm, and spoilage speeds up. Too cold, and carbonation can be lost or beer lines may freeze. Maintaining a stable, cool environment helps preserve both flavour and shelf life.
Beer Line Hygiene
Dirty lines create the perfect environment for microbial contamination. Yeast, mould, and bacteria build up over time, affecting taste and reducing the lifespan of even fresh kegs. A strict cleaning schedule—every 1–2 weeks—is essential to keep beer clean and crisp.
Frequency of Use
High turnover keeps beer moving and fresh. But if a keg sits on tap for too long, the risk of spoilage rises. Low-volume lines should be monitored closely, and staff should rotate stock to avoid forgotten, half-used kegs being served past their prime.
Together, these factors shape how long your draught beer lasts. And while some are easy to control, others—like gas purity—are often overlooked. That’s where Sure Purity’s expertise comes in, helping bars and breweries reduce spoilage without compromising on quality.
Typical Lifespan of Draught Beer
Not all draught beer is created equal when it comes to shelf life. From mass-produced lagers to hand-pulled cask ales, how long a beer lasts after tapping depends on what type it is (and how well it’s stored and served).
Below is a practical guide to draught beer lifespans under ideal conditions:
| Type of Beer | Expected Shelf Life After Tapping | Notes |
| Pasteurised Beer | 60–90 days | Common in large breweries. Needs consistent gas and temp. |
| Unpasteurised Beer | 30–45 days | Fresher, but more sensitive to hygiene and storage. |
| Cask Ale (Gravity-Pulled) | 3–7 days | No added gas. Highly perishable once opened. |
These timelines are best-case scenarios. They assume clean beer lines, steady cellar temperatures, and correct gas pressure. Any lapse in hygiene, temperature control, or pressure regulation can shorten a keg’s life dramatically.
One factor often overlooked is gas purity. Impure CO₂ or mixed gases can introduce contaminants that spoil beer faster and damage flavour. Even trace levels of sulphur compounds or benzene can lead to poor taste and wasted product.
Sure Purity’s Carboguard filters help tackle this by ensuring only high-purity, food-grade gas reaches your beer. With the right filtration, your kegs can reach their maximum lifespan while delivering consistent quality from the first pint to the last.
How Gas Purity Influences Beer Freshness
Behind every perfect pint is more than just good beer — it’s clean, stable gas. CO₂ doesn’t just push beer from keg to tap. It’s also a key part of preserving freshness and carbonation. But if your gas supply is compromised, the beer’s quality won’t last.
Poor-quality CO₂ can contain impurities like benzene, sulphur compounds, hydrocarbons, or even oil vapour. These contaminants don’t just alter taste — they can trigger spoilage and shorten the beer’s usable life. You may notice:
- Off-flavours (like a sulphurous or metallic aftertaste)
- Loss of head retention and carbonation
- Cloudiness or early oxidisation
Over time, using impure gas risks damage to your brand and an increase in waste.
That’s why industry bodies like the International Society of Beverage Technologists (ISBT) and the European Industrial Gases Association (EIGA) set strict standards for gas purity in beverages. But even certified “food-grade” gas can pick up contaminants between cylinder and dispense — through regulators, pipework, or the environment.
Our Carboguard Mini & Carboguard filtration system captures harmful impurities at the point of dispense. This final line of defence ensures only clean, odourless, high-purity CO₂ reaches your beer — helping preserve freshness from the first pint to the last.
By filtering out contaminants before they touch your product, you extend keg shelf life, protect taste, and give your customers a consistent, high-quality drinking experience.
Tips to Make Draught Beer Last Longer
Keeping draught beer fresh doesn’t need to be complicated. Simple, consistent practices can significantly extend shelf life and protect taste. Here’s what to prioritise:
- Store kegs at a stable, cool temperature
Aim for 11–13°C in a well-ventilated cellar or keg room. Avoid temperature swings. - Clean beer lines regularly
Every 1–2 weeks, flush lines to remove yeast, biofilm, and bacteria that cause off-flavours. - Check CO₂ regulator settings
Confirm the pressure matches the beer style and system. Incorrect PSI can damage carbonation or introduce air. - Install gas filters at the point of dispense
Filters like Sure Purity’s Carboguard remove contaminants before they reach your beer, preserving taste and shelf life. - Avoid leaving kegs untapped for long periods
Rotate stock and monitor tap activity. Once tapped, beer begins to degrade — even with best practices in place.
Each of these steps is small, but together they add up. Cleaner gas, cleaner lines, and better storage mean fewer returns, longer shelf life. This all leads to a stronger reputation for consistently great beer.
Signs Your Draught Beer Has Gone Bad
Even with careful handling, draught beer can spoil — and knowing the signs protects your customers and your reputation. Look out for:
- Sour or stale smell
A strong vinegar, musty, or overly sweet aroma could mean bacterial growth or oxidation. - Unusual foam or no head retention
Flat pours, foamy gushers, or no head at all can point to line issues, pressure imbalance, or stale beer. - Unexpected cloudiness or sediment
If the beer isn’t naturally hazy and you spot floating particles or haze, it could be contaminated. - Off taste
Watch for metallic tang, buttery notes (diacetyl), or sulphuric/rotten egg flavours — all signs of spoilage or gas impurities.
If in doubt, test it. Never serve beer that tastes or smells off. One bad pint can cost more than just a refund. It can cost your business its reputation, and the loyalty of your customers.
Sustainable Draught Management
Sustainability in the drinks industry isn’t just a buzzword — it’s a practical way to cut costs, reduce waste, and protect long-term profitability. Efficient draught beer management plays a key role in this effort. When you maintain freshness and avoid spoilage, you serve more of what you pay for and waste far less. This not only improves your margins but reduces the environmental impact of throwing away unsold beer.
Sure Purity supports this approach through longer-lasting gas filtration. Traditional gas filters often need changing every six months. In contrast, Sure Purity’s Carboguard filters last 12 months, cutting filter changes in half. That means fewer materials used, fewer deliveries, and less energy spent on manufacturing and disposal — all contributing to a smaller carbon footprint.
Every keg saved and every filter spared adds up across a venue, chain, or brewery. By switching to a cleaner gas system, operators can meet sustainability targets without compromising performance. It’s a simple equation: cleaner gas, better beer, reduced footprint.
Conclusion – The Right Setup Keeps Beer Fresher for Longer
Keeping draught beer fresh isn’t guesswork—it comes down to the right conditions behind the scenes. From the type of beer you serve to how you store and dispense it, every part of your system plays a role in how long your beer lasts and how good it tastes. Cleanliness, temperature control, and gas purity are the three cornerstones of draught beer quality.
Sure Purity’s Carboguard filters support longer shelf life by delivering clean, food-grade CO₂ that protects against contamination. With 12-month lifespan filters, you not only improve beer quality but reduce solid waste by up to 50%. That’s a win for your cellar, your customers, and the planet.
Key Takeaways
- Draught beer shelf life varies depending on type, storage, gas quality, and hygiene.
- Pasteurised beers last 60–90 days, while unpasteurised and cask ales spoil much faster.
- Poor gas purity can cause spoilage by introducing contaminants like benzene or sulphur.
- Line cleanliness and stable temperatures are essential for freshness and taste.
- Sure Purity’s Carboguard filters help extend beer life by ensuring clean, food-grade CO₂.
- Fewer filter changes mean less waste, lower emissions, and a more sustainable cellar setup.
- Simple changes to your dispense system can save money, reduce waste, and protect your reputation.
If you’re serious about preserving flavour, reducing waste, and getting more from every keg, it’s worth reviewing your setup. Learn how Carboguard can protect your pour and your margins. Contact us today.
