How much does wasting draught beer cost a Retailer?

By Keith Lemcke
July 04, 2022

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If you have spent any time at a bar or restaurant that serves draught (draft) beer, you have probably seen bartenders dump out beer foam for a number of reasons. Since “it’s mostly just CO2”, it should be no problem to let it run down the drain, right? Actually, foam loss can add up to real dollars lost in a very short time.

When a draught beer system is engineered, the system should be designed in such a way as to create an attractive collar of foam on every glass poured. Yet even well-designed systems occasionally suffer from problematic foaming. When faced with over-foaming issues, bartenders sometimes just allow the excess foam to overflow from the glass down into the drip pan below the faucets, letting ounce after ounce flow until the beer in the glass is mostly liquid. These bartenders may not know (or care) that every 4 ounces of foam contains approximately 1 ounce of liquid beer, so allowing foam to flow uncontrolled into the drip tray is very much the same as just pouring beer down the drain.

There is sometimes an attitude that losing beer down the drain doesn’t cost much when based on the cost of a keg, but the more useful metric is how much beer is being wasted by its retail value. For example, let’s say a beer sells at your bar for $4.00 for a 16-ounce pour, making that beer worth 25 cents an ounce. If your bartenders have a habit of wasting 4 ounces of beer foam with each pint poured by letting it flow out of the glass, it means your business loses 25¢ of retail sales value per pint. Pouring out a 16-ounce pint glass full of foam from a problematic keg means your business loses one dollar’s worth of beer at retail. That doesn’t sound like much until you do a bit more math.

A loss of 25¢ worth of beer per pint served calculates to about $30 of lost sales potential per 15.5 US-gallon (1/2 barrel) keg. The figures below give you the basic math.


1/2 barrel keg volume in ounces 1984 oz
16 ounce glasses per keg 124 pints
Retail $ amount lost with the waste of 1 ounce per glass poured at 25 cents per ounce retail price $31.00 retail value



That should be a concern to any bar owner, but let’s dig a bit further into the figures. A $4 dollar beer is an inexpensive beer compared to many of the craft brews and imported brands on the market, so when you look at some of the higher-value lagers and ales being served, the cost per lost ounce climbs pretty rapidly. By the time your pint has a retail value of $8 or more, the foam losses are equal to over 50 cents per ounce. If the discarding of foam applies to all the beers being served at the bar, let’s extend this concept to the total potential financial losses per year. If we stay on the 25¢ value and the one-ounce-per-pint-loss figures, here’s where the numbers really tell the tale.



Retail amount lost per keg served 31.00
Total annual losses based on keg changes per week
1 keg change per week 1,612.00
2 keg changes per week 3,224.00
3 keg changes per week 4,836.00
4 keg changes per week 6,448.00
5 keg changes per week 8,060.00
6 keg changes per week 9,672.00
7 keg changes per week 11,284.00
8 keg changes per week 12,896.00
9 keg changes per week 14,508.00
10 keg changes per week 16,120.00


Since it is common for many bars to change more than 10 kegs a day, the potential for this sort of loss is substantial. “Many owners and managers overlook the unwanted foam from an unbalanced system that is poured out with each beer. One or two ounces at a time is easy to ignore but added up over a year is a significant loss of potential revenue” says Drew Larson, CEO of Leaders Beverage, a leading US Midwest draught service company.

The speed of beer loss from an open tap that has no glass underneath it is also a huge concern. The average draught faucet flows at a rate of 1 gallon per minute. That means for every second a faucet is opened without a glass underneath it to catch the beer, 2 ounces of beer goes straight into the drain. It is like putting dollar bills into a shredder.

Any bar offering draught service can maximize profits by minimizing draught loss, and the process all starts with training, especially of bartenders and general managers. The first place to take action is in how beer is being poured. Some bartenders open a faucet to start the flow of beer before putting a glass under it for a multitude of perceived reasons including to get rid of any flying insects that may be in the faucet mouth. If insects are an issue, a very quick open-close of the faucet should achieve the goal of getting rid of them before pouring the beer. More commonly, draught systems can exhibit foam problems from unknown causes, including some issues that pour dramatic amounts of foam. While staff can simply stop a pour when the foam gets too high and wait for it to subside until pouring more liquid beer, there are frequently situations when there is so much foam that waiting to fill a glass with liquid beer is impractical.

In situations like this, troubleshooting through a step-by-step approach is the best way to eliminate the source of the issue, but there are a lot of potential causes for over-foaming that make correcting the problem a difficult task. The Draught Quality Manual website offers an excellent resource for learning about the causes of draught problems, but it isn’t meant as a “how-to” book for having unqualified people adjust a draught system. In fact, only someone who has training in draught design and service should generally attempt to adjust a draught system. Any bar or restaurant that serves even a nominal volume of draught should have at least one person formally educated in draught-related issues. It will help them to be able to spot the causes of draught problems, and to know whether they can personally take corrective measures or if they should call in a trained draught technician to solve the issue. This is especially the case for chronic draught issues such as ongoing foam problems. A qualified, well-educated draught technician should be able to correct any major draught problem, with a quick return on the investment by lessening beer loss and maximizing per-keg revenue.

To gain a complete understanding of the sciences and technologies that lead to serving perfect draught beer, enroll in the Siebel Institute Draught Master course. Details are at .

Keith Lemcke is an Education Consultant at Siebel Institute of Technology. Keith is a 2022 member of the Draught Quality committee and Draught Safety committee of the Brewers Association and a past Executive Director of the Draught Beer Guild.