Nine Draught System Problems That Are Costing You Money. And None of Them Are Your Bar Staff’s Fault.
- David Holden
- Jun 30
- 6 min read
Updated: 1 day ago
Draught Beer Series - Part 2.
In the last post I put a number on draught beer loss: £27,000 a year for a ten-tap venue losing 1.5 pints per tap per day. If that landed, the obvious question is where it’s actually coming from.
The answer, in most venues, is the system. Not the people behind the bar. The infrastructure they’re working with.
Here are the nine places to look.
1. Beer Temperature
One of the biggest drivers of pour cost, and one of the most expensive to ignore.
Cellar air temperature should sit around 12°C, and that's non-negotiable if cask ale is on the same stillage. Keg beer is then chilled further on its way to the tap, typically through a remote cooler or python system, to arrive cold enough to maintain carbonation and pour quality. Small temperature variations at either stage can have a significant impact on the amount of foam produced during dispense.
Too warm means excess foam and wasted product every time the tap opens.
Too cold can affect carbonation balance, presentation, and drinking quality, leading to corrective over-pouring and inconsistent serves.
The practical issue is delivery. A keg arriving warm can take 12 hours in the cellar to come down to temperature. Put it straight on and you're pouring foam from the first pull.
2. Flow Rate
Pour time varies by product. Lagers and ciders typically take 14 to 16 seconds. Stouts, craft beers, and ales run longer, generally 16 to 22 seconds.
Too slow and CO₂ breaks out before the beer reaches the glass.
Too fast and you create turbulence, foam, and inconsistent serves.
Flow rate is controlled by gas pressure and line setup. If it's wrong, it's a calibration issue, not a staff issue.
3. Gas and Pressure
Incorrect gas setup is one of the most common causes of persistent pour issues.
Gas type isn't determined by line length. It's set by the brand owner's specification for that product, and most brand owners give a first and second choice gas, which matters when taking over another brewery's lines.
On longer runs, pressure is usually maintained with a pump-assisted system rather than switching to a different gas blend. The correct pressure depends on the beer, temperature, carbonation level, and system design, set against the brand owner's spec rather than distance alone.
Compressed air should never be used. Gas blends must be correctly specified for the system. Incorrect ratios create ongoing quality and wastage issues.
4. Line Cleanliness
This is where many venues are losing money without realising it.
Lines that look clean aren't. The contaminants that affect beer quality are often invisible until they're well established.
Yeast build-up causes fobbing and off flavours. Bacteria produce sour, vinegary, or buttery notes often blamed on the keg. Beerstone develops over time and isn't removed by routine cleaning alone.
Best practice is a full line clean every seven days, particularly for high-volume and long-draw systems. Some industry standards permit longer intervals, but extending cleaning cycles invariably increases risk to both quality and yield.
Nozzles and sparklers should be removed and cleaned at the end of each day. Drip trays should be rinsed daily.
If you wait until lines look dirty, you're already losing money on every pour.
Low and no-alcohol draught lines require even more attention, as they spoil faster without alcohol acting as a preservative.
It's also worth asking the commercial question alongside the technical one. Do your sales of non-alcoholic draught actually justify stocking it? With faster spoilage and the extra line discipline required, a low-volume line can become a liability rather than an asset.
5. Pour Technique
A well-maintained system will still lose money if the pour isn’t consistent. That’s a people issue, but it only becomes relevant once the system is right.
That’s the subject of the next post.
6. Line Condition
Lines should run continuously upward from keg to tap with no kinks, sags, or sections that trap liquid. Any break in that upward run creates a pocket where beer sits, warms, and generates foam before it even reaches the tap.
In long-draw installations, the glycol cooling system must maintain temperature throughout. A warm section anywhere in the run means foam on every pour through it.
Line condition is checked during installation but rarely inspected again unless there's a persistent problem. It should be part of the maintenance checklist.
7. FOB Detectors
A FOB detector (foam on beer device) sits between the keg and the beer line. When a keg empties, a float inside the unit drops and shuts off the line before air gets in.
Tap a new keg, reset the FOB, and beer flows again without purging a line full of foam first.
Without one, every keg change means losing the beer left in the line to foam. On a busy bar changing multiple kegs a shift, that’s a meaningful volume of product tipped away every single week. FOB detectors pay for themselves in reduced keg-change waste, particularly in high-volume operations.
8. Glassware
Regardless of how well the cellar is managed and how well the system is set up, unfit glassware ruins the pour at the final moment.
Beer glasses must be clean, cool, dry, unchipped, and free from residue.
The symptoms of poor glassware are easy to spot:
Bubbles clinging to the interior of the glass
A cloudy or milky appearance after washing
Beer losing its head immediately
Poor lacing after drinking
The cause is usually grease or residue from detergent, lipstick, food handling, or tea towels used to dry glasses.
Drying glasses with a cloth leaves a film that can collapse carbonation. Glasses should air dry on a ventilated rack, never double-stacked, never cloth-dried.
Over time, glasses build up an invisible layer of sugars, proteins, hop resins, and detergent residue that regular washing doesn't fully remove.
A glass renovation treatment strips this back.
The test is simple:
Rinse with cold water, invert the glass and hold it to the light.
If the water sheets off in a continuous film, the glass is clean.
If it breaks into droplets or patches, the glass needs renovating.
New glasses should also be renovated before first use, as many arrive with manufacturing residues that affect dispense quality.
The glasswasher itself needs maintaining too.
Wash temperatures should generally sit around 50–55°C, with rinse temperatures around 60–65°C, following the manufacturer's specification.
Only glassware should go in.
Crockery, cutlery, and drip trays interfere with detergent performance and reduce washing effectiveness.
The machine should be drained regularly and left open after cleaning to prevent microbial growth in the warm, damp interior.
9. Faulty Equipment
Equipment faults are more common than most operators realise, and every hour one goes unaddressed is an hour of compounding loss.
Fobbing at the font is one of the most visible symptoms, but the cause isn't always obvious. Worn tap seals and washers restrict liquid flow and force CO₂ out of solution before the beer reaches the glass.
Dirty tap components, where yeast, sugar, and bacteria have accumulated inside the nozzle, create nucleation points that turn smooth beer into foam on every pour.
A damaged coupler with a torn seal allows gas to enter the beer stream.
Incorrect line size or a kink in the tubing causes pressure drops that separate gas from beer before it reaches the tap.
Physical leaks are just as damaging and easier to miss because the losses happen quietly...
A worn washer causes the tap to drip constantly between pours.
A loose bonnet nut produces a slow leak throughout service.
Damaged hose clamps drip behind the bar and allow air into the system.
Ageing or damaged lines introduce oxygen and compromise product quality before the beer even reaches the font.
A remote cooler struggling to hold temperature will create foam issues with no obvious cause visible at the bar.
A failed cellar cooling system can slowly push temperatures across the entire cellar out of specification.
These are infrastructure failures, not operational ones, and they become more expensive the longer they're ignored.
The answer is a daily walk-around.
Before service, a manager or cellar-responsible team member should check:
Cellar temperature
Remote cooler operation
Font performance on every tap
Gas cylinder levels
Leaks, drips, unusual noises, or unusual smells
It takes ten minutes.
It catches faults while they're still small.
A callout on the day a fault is spotted costs less than a week of losses before anyone notices something is off.
Equipment faults spotted early get fixed.
Equipment faults that go unnoticed become expensive habits.
The compounding problem
Most venues aren’t dealing with one of these issues. They’re dealing with several simultaneously. Each one adds a small amount of loss to every pour. Together they explain the gap between what the draught operation should produce and what it actually does.
Fix the system and the numbers improve. But even a well-maintained system loses money if the pour technique isn’t consistent across the team. That’s next.
This is Part 2 of The Draught Beer series, you can view the other blogs here....
For the full picture on draught operations from cellar to glass, the Clarity by David Holden Draught Beer FAQ covers 24 common questions across every area of the draught system.
If your draught set-up is underperforming and you want to know where the loss is coming from, a Profit Review will tell you. No pitch, no prep. Just a straight conversation about where your margin is going.
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