The figures below were calculated by yours truly from many actual craft breweries in the US with data from 2004 through 2007. The formula is simple, total wastewater produced divided by barrels brewed based on monthly data.
The figures below are an annual average of the monthly averages. Notice it is barrels brewed, not barrels sold or barrels packaged. Also note it is total wastewater produced (side stream plus low strength). 1 barrel (bbl) = 31 gallons.
*All of these figures are for production breweries without restaurants in site.
**Twice I have worked with small brewers who were getting 1 bbl ww/bbl of beer brewed!
(The Brewers Association Sustainability Subcommittee maintains a more current list of these numbers, but they agree with what I have here)
- Very dialed in, well managed brewery: 2 bbls ww/bbl of beer brewed
- Moderately well managed brewery: 3 bbls ww/bbl
- Brewers with no water constraints but have been in production for several years: 4 bbls ww/bbl
- Startup breweries doing their first few batches: 5 bbls ww/bbl of beer brewed or more
If you are planning a brewery, how can you know how much wastewater you will produce? With this information you can come up with a pretty good estimate. Let’s assume you will produce 1,000 barrels in your first year. Assume your first 6 months will be at 5 bbls ww/bbl and your second 6 months will be at 4.5 bbls ww/bbl:
500*5*31 = 77,500 gallons, plus
500*4.5*31 = 69,750 gallons; for a total of 147,250 gallons of total wastewater in that first year. You can further do the math to calculate gallons per month or day.
If you are already running your brewery, you probably have the data to calculate your wastewater per barrel figure. How you compare to the above figures is good to know, but more important is simply to know where you are. Growth plans in your future? Now you can accurately forecast your future wastewater quantities.
This same methodology works in all sorts of applications. Caustic usage per bbl, KWH usage per bbl, therms/bbl, people/bbl, man hours/bbl, incoming water/bbl. The list goes on. At Deschutes I would track energy usage figures each month and we would track company wide performance based on these numbers- among many other factors of course. These numbers are especially handy at budget time, and you can get very accurate figures as you get better at it. You can see the effects of seasons on your energy usage. You can see the results of various process improvements on appropriate usage figures. This is a project that is very worth doing.