Line cleaning bins about 20 pints a week. Your stocktake needs to know that

UK pubs throw away around 40 million pints a year cleaning beer lines. For the average pub that's about 20 pints a week, and at 2026's average pint price of £5.34 that's roughly £107 a week of retail value down the cellar drain, call it £5,500 a year. Nobody should skip cleaning to save it, dirty lines cost more than clean ones ever will. But every one of those pints was bought, duty paid, and never sold, and if your stocktake doesn't know where they went, they turn up somewhere worse: your variance. Here's the arithmetic, and the fix.

Where the beer actually goes

Two places. First, the line itself. Standard 3/8 inch bore python holds about a pint and a quarter for every 10 metres of run. A bar sat directly over its cellar might have 5-metre runs, two thirds of a pint a line. A remote cellar down a corridor and round a corner can easily mean 15 to 25 metres, so two to three pints sitting in every single line, and all of it goes to drain the moment the cleaning water goes in.

Second, the pull-through. When the clean is finished you pull beer through until you're certain no cleaner or water is left in the line, and cellar guides tell you to give it 2 to 3 pints extra per line to be sure. Rightly so. Serving someone caustic residue is a different order of problem to wasting beer, so nobody sensible skimps here. But it means a ten-tap bar on medium runs is binning around 20 pints per clean before a single drink has been poured. That's not sloppiness. That's how the plumbing works.

What that costs over a year

Beer sitting in the lines at each weekly clean, author's arithmetic from 3/8 inch bore and run length, valued at the Morning Advertiser's 2026 average pint of £5.34. Pull-through to clear cleaner adds more on top.

Setup	Pints in the lines per clean	Pints a year	Retail value a year
4 taps, 5m runs (bar over cellar)	2.5	130	£690
6 taps, 10m runs	7.5	390	£2,080
10 taps, 15m runs (remote cellar)	19	980	£5,220
12 taps, 25m runs (long remote runs)	38	1,960	£10,440

The national numbers back the arithmetic up. Beer Piper's research, reported by the Morning Advertiser in 2019, put line cleaning waste at 40 million pints a year across the UK, about 20 pints and £74 a week for the average pub when the average pint was £3.69. Rerun those 20 pints at today's £5.34 and it's £107 a week, £5,550 a year.

And there's a sting in the tail. About 50p of duty is baked into every 4.5% draught pint at the February 2026 rates. The brewer paid it, you paid the brewer, and duty on line cleaning waste is never coming back. The relief rules I set out in the ullage guide cover spoilt beer going back through the producer. Beer you deliberately ran to drain doesn't qualify and never has.

The seven-day argument

Brewery guidance says clean every seven days, and it's what every cellar course teaches. The industry's own data says plenty of pubs don't: the Vianet and Cask Marque beer quality report, built from 220,000 monitored dispense points and over 22,000 pub visits, found more than 30% of beer served in the UK came through lines that hadn't been cleaned inside the seven-day window.

The counter-argument exists and it isn't daft. Cellar service firms make the case that a properly done professional clean can hold a line for three or four weeks. Brewer-fitted kit goes further: Heineken's SmartDispense keeps the line cold enough that cleaning stretches to every six weeks, or every twelve on the newer version, and their own figures claim 85% less water wasted, around 8,000 pints of water a year on an average install. If your brewer offers you that kind of system, the beer and water savings are real arithmetic, so run the numbers on it.

My take is that cleaning cadence is a beer quality decision first and a waste decision a distant second. A cloudy pint handed back costs you the pint, the replacement, and a slice of that customer's confidence in your cellar, which is the expensive part. What matters for this guide is simpler: whatever cadence you settle on, keep it consistent and write it down, because your stocktake can't read your mind.

What it does to your stocktake

Here's the bit none of the cleaning guides mention. A pub selling 1,500 pints a week that bins 20 in a line clean has 1.3% of its draught volume leaving the building as completely legitimate waste. Put that against what counts as an acceptable variance and it swallows most of the band on its own. Unlogged, a spotless bar reads like a leaky one, and someone ends up hunting for a loss that was really the cleaning bucket.

The fix costs nothing. Work out what each line holds, length times bore gets you close, or catch what comes out at the next clean before the water hits and measure it once. That's your pints-per-clean number, and it barely changes until you change the lines. Then log it as waste every clean in whatever you count stock with. In StockTap that's a wastage entry against the product, and it means the variance report already has cleaning waste explained before you look at it, so the number left over is the one worth splitting into pouring, waste or measuring error. It changes the conversation with a stocktaker too. A calibrated cellar with a written waste log gets a very different hearing to a shrug.

If you want the number smaller

A few honest levers, none of them heroic. Know your line volumes so the pull-through is measured rather than generous, pulling three pints to be safe on a line that holds two thirds of a pint is charity to the drain, and pH papers cost pennies if you want certainty instead of guesswork. If you're ever refitting, every metre you take off a python run is beer saved 52 times a year for the life of the cellar. If your brewer offers cellar kit that extends the cleaning cycle, do the arithmetic above with your own tap count and see what it's worth. And the one lever not to pull: stretching the cadence purely to save beer. The 20 pints are visible and cheap. The trade you lose to a bad pint is invisible and isn't.

Common questions

How much beer does cleaning beer lines waste?

Research by line cleaning firm Beer Piper, reported by the Morning Advertiser in 2019, put it at around 40 million pints a year across UK pubs, about 20 pints a week for the average pub. Your own figure scales with tap count and line length: a 3/8 inch line holds about a pint and a quarter per 10 metres, all of it lost at each clean, plus the pull-through needed afterwards to clear cleaner and water from every line.

How often should beer lines be cleaned?

Standard brewery and cellar guidance is every seven days. Industry monitoring reported in 2017, drawn from 220,000 dispense points, found over 30% of beer served in the UK came through lines outside that window. Brewer-fitted systems such as Heineken SmartDispense stretch cleaning to every six weeks, or twelve on newer kit. Set your cadence on beer quality grounds, then keep it consistent so your stocktake can rely on it.

Can a pub claim beer duty back on line cleaning waste?

No. Duty relief on spoilt beer runs through the producer, who claims it and passes a credit back via your supplier, and it covers beer that is spoilt or unfit. Beer deliberately run to drain during line cleaning has never been claimable. At 2026 rates a 4.5% draught pint carries about 50p of duty, and every pint you pull through to waste takes that duty with it.

How many pints of beer sit in a beer line?

Standard 3/8 inch bore python holds roughly a pint and a quarter per 10 metres of run. A bar directly over its cellar with 5-metre runs has about two thirds of a pint in each line. A remote cellar 25 metres away has over three pints in every line, and it all goes to drain when the cleaning water goes in.

Should line cleaning waste go through the stocktake?

Yes, logged as waste on the night. Twenty pints a week is over 1% of draught volume in an average wet-led pub, which is most or all of a normal acceptable variance band on its own. Log it and your variance report shows only what's actually unexplained. Leave it out and a clean-running bar looks like a leaky one.