DRAUGHT BEER
FAQ'S
Common questions about cellar management, dispense systems, line cleaning, equipment, glassware, and pour technique.
Answered plainly for operators who want
to protect their margins.
Cellar and Temperature
Why is cellar temperature important for draught beer?
Cellar temperature directly affects the quality and yield of every pint you serve. Beer that is too warm produces excess foam on every pour, wasting product and reducing yield. Beer that is too cold produces flat, lifeless pints with no head, which staff tend to compensate for by over-pouring. Both cost you money.
The target cellar air temperature is 11 to 13 degrees Celsius. Outside that range, no amount of good technique at the bar will produce a consistent, profitable pour.
How long does a keg need to chill before serving?
Longer than most operators allow. A keg arriving at ambient temperature needs up to 25 hours in the cellar before it reaches correct serving temperature. One that feels cold to the touch at around 8 degrees Celsius still needs 18 hours.
Putting a keg straight onto service is one of the most common and costly mistakes in draught operations. The result is foam on every pour until the keg reaches the right temperature, and that foam is product you have paid for and are throwing away.
What temperature should my cellar be?
Cellar air temperature should sit around 12 degrees Celsius, and that's non-negotiable if cask ale is on the same stillage.
Keg beer is 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.
These are not approximate figures. Running outside this range affects every pour on every tap, cask especially.
Gas and Pressure
What happens if kegs are delivered warm?
A warm keg will need around 12 hours to come down to temperature, so kegs delivered warm start costing money before they are even connected. If they go straight onto service without adequate chilling time, every pour will be foam-heavy until the keg stabilises.
In busy operations where kegs are turned around quickly, warm deliveries that go straight on are a consistent, invisible drain on yield. Check delivery temperatures and rotate stock so new kegs have time to chill properly before they are needed.
What gas should I use for my draught beer system?
Gas type is determined by the brand owner's specification for that product, and most brand owners give a first and second choice gas, which matters if you're taking over another brewery's lines. On longer runs, the answer to maintaining pressure is usually a pump-assisted system rather than switching to a mixed gas blend. If your gas setup hasn't been checked against the brand owner's spec, it's worth having it reviewed.
Why does my draught beer taste flat?
Flat beer is usually a gas or temperature problem. The most common causes are incorrect gas mixture for brand's specification, pressure set too low, beer served too cold, or dirty glassware that collapses carbonation on contact. Dirty beer lines can also produce off-flavours that present as flatness.
Check gas pressure and mixture first, then cellar and serving temperature, then glassware condition. If all three are correct and the beer is still flat, the lines need cleaning.
Line
Cleaning
Can I use compressed air to dispense draught beer?
Absolutely not. Compressed air must never be used to dispense draught beer. Air introduces oxygen into the beer, which causes rapid oxidation and spoilage. It also introduces bacteria and contaminants that affect flavour and can make the beer unsafe to serve.
CO2 and nitrogen are inert gases that protect the beer during dispense. Compressed air does neither. Any system running on compressed air should be corrected immediately.
How often should beer lines be cleaned?
Every seven days as a minimum. Unless proprietary dispense equipment is installed that extends the cleaning interval, weekly cleaning is the standard required to prevent biofilm, yeast, bacteria, and mould from building up inside the lines.
Any money saved by cleaning less frequently is outweighed by increased wastage, off-flavours, and reduced sales. Low and no-alcohol draught lines may need more frequent cleaning as the absence of alcohol removes a natural defence against microbial growth.
What happens if beer lines are not cleaned regularly?
Contaminants build up quickly. Yeast accumulates and causes excessive fobbing and off-flavours.
Bacteria produce sour, vinegary, or butterscotch tastes that operators often blame on the keg rather than the line. Mould develops where air meets damp conditions and can enter the system during a keg change. Beerstone builds up as a brown deposit that affects flavour and restricts flow. None of these are visible until they have been building for some time.
By the time the problem is obvious, it has already been affecting every pour for weeks.
Equipment
and Faults
What is beerstone and how do I remove it?
Beerstone is calcium oxalate, a brown deposit formed by a chemical reaction between oxalic acid produced during the brewing process and calcium from the water. It builds up on the inside of beer lines, faucets, and couplers over time and is not removed by standard caustic line cleaning. It requires an acid clean, which should be carried out quarterly in addition to the regular weekly caustic clean.
Beerstone affects the flavour of beer and provides a surface where bacteria can attach and grow. If lines have not been acid cleaned for some time, a thorough clean may be needed before the deposit is fully cleared.
Do low and no-alcohol draught lines need more frequent cleaning?
Yes. Alcohol in beer acts as a natural defence against microbial spoilage in the lines. Low and no-alcohol beers lack this defence, making them significantly more susceptible to bacterial growth, off-flavours, and spoilage.
If you serve draught low or no-alcohol products, those lines should be cleaned more frequently than your standard weekly schedule. The exact frequency depends on the product and volume, but err on the side of more rather than less. A spoiled no-alcohol pint is the same lost margin as any other.
Why is my draught beer foamy?
Persistent foam at the font usually comes from one of several equipment or system issues.
Worn tap seals and washers restrict flow and force CO2 out of solution before the beer reaches the glass. Dirty tap components create nucleation points inside the nozzle where gas bubbles form and turn smooth beer to foam.
A damaged coupler with a torn seal allows compressed gas to leak directly into the beer stream. Incorrect line size or a kink in the tubing drops pressure mid-run and causes gas to separate from the beer before it reaches the tap.
Incorrect gas pressure set too high pushes the beer too aggressively and causes foam in the glass. Check these in order before adjusting anything else.
What causes a beer tap to drip or leak?
Most drips and leaks come from worn or damaged internal components.
A worn piston or ball washer on the end of the faucet shaft causes the tap to drip constantly between pours.
A loose bonnet nut produces a slow, steady leak from the nozzle throughout service.
Damaged or rusted hose clamps at the line connections drip behind the bar and allow air into the system, which affects the quality of every pour that follows.
Pinhole leaks in aged or over-flexed beer lines introduce oxygen and ruin the beer's condition before it reaches the font.
These faults are easy to miss because the losses happen quietly.
A daily check of fonts and connections catches them before they become expensive.
What is a FOB detector and do I need one?
A FOB detector, or foam on beer device, sits between the keg and the beer line. It contains a float that rises with beer flow and drops when a keg empties, shutting off the line before air gets in. When you tap a new keg, you reset the FOB, vent the chamber, and beer flows again without needing to purge a line full of foam.
Without a FOB, every keg change means losing the beer left in the line to foam before the flow stabilises. On a busy bar changing multiple kegs per shift, that adds up to significant volume every week.
FOB detectors are particularly valuable on long-draw systems where the line holds more beer. They pay for themselves quickly in reduced keg-change waste.
If you're losing on keg changes with a FOB detector you need to call out your cellar technician.
How do I know if my coupler is damaged?
The most common signs are excessive fobbing at the font that has no other obvious cause, gas leaking audibly when a keg is connected, and beer spitting or surging at the tap rather than flowing smoothly. A damaged coupler seal allows compressed gas to enter the beer stream directly, which causes severe foaming and an inconsistent pour.
Couplers should be inspected regularly for torn or flattened seals, cracks in the body, and loose connections. If a coupler is suspect, replace it. The cost of a new coupler is negligible compared to the loss from a session of foamy pours.
Glassware
What should I check on a daily walk-around of my cellar?
A daily walk-around before service takes around ten minutes and is one of the most effective things a manager can do to protect draught margins.
Check cellar temperature and compare it against the target range.
Check the remote cooler is operating correctly and holding temperature.
Inspect each font for drips, leaks, or unusual fobbing.
Check gas cylinder levels and ensure the correct gas is connected to each line.
Look and listen for anything that seems wrong: unusual sounds, smells, or visual signs of leaks.
Log anything that needs attention and act on it the same day.
A fault spotted early costs a callout fee. A fault left running for a week costs a callout fee plus days of losses.
Why does my beer lose its head quickly in the glass?
Head collapse is almost always a glassware problem. Grease, detergent residue, lipstick, or food contamination on the inside of the glass collapses carbonation on contact with the beer. Drying glasses with a cloth is one of the most common causes as it leaves an invisible greasy film across the interior surface. Glasses that have been double-stacked trap moisture and odours that affect head retention.
Over time, glasses build up residue from sugars, proteins, hop resins, and detergents that regular washing does not fully remove, and this requires a renovation treatment to clear.
What is the water break test?
The water break test is a simple check for glassware cleanliness. Rinse a glass with cold water, discard the water, invert the glass and hold it up to a bright light. If the water sheets off in a continuous film down the inside of the glass, the glass is clean and free from residue. If the water breaks up into patches and spots, the glass contains grease or residue and needs renovating before use.
It takes seconds and should be used routinely, particularly when glasses are returning from a new glasswasher cycle or when head retention problems are being investigated.
Pour Technique & Management
How should beer glasses be stored?
Glasses should be stored upright or inverted on a ventilated rack or shelf with webbed matting, never double-stacked. Stacking traps moisture and encourages odour build-up inside the glass, both of which affect the quality of the pour. Glasses should be stored in cool conditions and allowed adequate drying time after washing. They should never be dried with a cloth or tea towel as this deposits grease onto the interior surface. Chilled glass storage should be between 2 and 4 degrees Celsius.
Freezer storage is not appropriate as it causes condensation on the glass which disrupts carbonation.
What is glass renovation and when is it needed?
Glass renovation is a treatment that removes the invisible layer of sugars, proteins, hop resins, and detergent residue that builds up on glassware over time through regular use. Standard glasswashing removes surface contamination but does not fully strip this residue, which gradually worsens head retention and affects beer quality.
Renovation should be carried out regularly on all glassware in active use, with higher-volume bars needing more frequent treatment. It is also required on all new glasses before first use, as new glassware comes coated in a manufacturing lubricant that causes the same problems. The water break test will tell you when renovation is needed.
What is the correct way to pour a pint?
Start with a clean, cold, dry glass with no fingerprints near the rim. Hold the glass at 45 degrees under the tap with the nozzle not touching the glass or the beer. Open the tap fully in one smooth movement. A half-open tap creates turbulent flow that generates foam. Straighten the glass gradually as the beer rises and let the head build naturally. Stop when the head reaches the brim. For lagers and stouts requiring a two-part pour, allow the full settling time before topping up. Do not rush it. Check the pint visually before serving.
The whole process should take around four seconds of active pouring for a standard pint.
How do I know if my bar staff are pouring correctly?
Watch the tap. A half-open tap is the most common fault and is visible immediately. Watch the glass angle at the start of the pour and whether the nozzle is touching the glass or the beer. Watch whether staff are starting the pour before the glass is positioned under the font. That single habit wastes around 50ml of beer into the drip tray before the pour has even started. Across a busy team on a Friday night, that loss is significant and consistent. Observe whether two-part pours are being rushed and whether a visual check is happening before the pint goes to the customer.
What should I be looking for in drip tray wastage?
Drip trays should be monitored daily and the volume cross-referenced against the rota. Patterns become evident quickly. If the drip tray is consistently fuller on certain shifts, you have a technique issue tied to specific team members rather than a system problem. That is a precise, actionable finding. It tells you exactly where the conversation needs to happen.
Drip tray monitoring is one of the simplest and most underused management tools in draught operations. It requires no equipment, no software, and no analysis. It just requires someone looking at it consistently and asking why.
How do I reduce draught beer losses across my operation?
Start with tracking. Compare actual keg usage against POS sales data weekly. If kegs are emptying faster than the sales data justifies, you have a loss somewhere in the system. Then work through the nine causes systematically: temperature, flow rate, gas and pressure, line cleanliness, line condition, FOB detectors, glassware, faulty equipment, and pour technique. Most venues are losing on more than one simultaneously. Fix the system first, then address technique. Once both are in order, keep measuring.
Draught beer loss is recoverable but it drifts back without consistent management attention. Weekly tracking, daily walk-arounds, and real-time coaching on technique are the three habits that protect draught margin long-term.