Water is the most important raw material in beer production and influences all phases of the brewing process. The water quality requirements vary depending on the intended use - be it in brewing, cleaning, cooling or steam generation. In a brewery, water is therefore not just water - each type of water fulfills a specific function and must be matched to its respective task.
In this article, we take a look at the different aspects of water use in breweries - from the requirements for brewing water and its composition to the importance of water hardness and the challenges of waste water.
Water - the most important raw material in beer production
A beer with an original gravity (the main factor influencing the subsequent alcohol content) of twelve percent consists of around 90-92% water; the rest is made up of alcohol, extract substances and carbon dioxide. This means that water is the main component of the finished beer. However, water is not only used as brewing water in breweries. Cleaning and cooling processes account for a significant proportion of total water consumption. In larger breweries that operate steam systems, boiler feed water is also required to supply the steam boiler with water.
Water consumption per hectoliter (hl) of beer sold is used to assess
operational efficiency. Depending on the degree of industrialization, this is usually between 3 and 6 hl of water per hl of beer. This value can be significantly reduced through targeted water management - for example through the use of recirculation systems or modern cleaning technologies. Breweries that pursue comprehensive sustainability concepts are now even achieving consumption levels of less than 2 hl of water per hl of beer.
Brewing water - quality requirements and composition
Brewing water must not only meet the requirements of the Drinking Water Ordinance, but also have specific brewing technology properties that have a positive effect on beer production. The content of dissolved salts has a significant influence here. These include compounds of positively charged metal ions - in particular calcium (Ca²⁺) and magnesium (Mg²⁺) - with negatively charged ions, the so-called acid residues, such as carbonate (from carbonic acid) or sulphate (from sulphuric acid).
The concentration of these compounds or salts is usually specified as the “
German degree of hardness” (°dH):
- 1 °dH corresponds to 10 mg of calcium oxide (CaO) per liter of water.
- The degree of hardness indicates the “total hardness”, i.e. the total sum of calcium and magnesium salts belonging to carbonic acid, sulphuric acid or another acid residue.
- In the brewing and fermentation process, calcium and magnesium salts promote enzymatic reactions, regulate the pH value of the mash and influence the taste and stability of the beer.
The degrees of hardness are classified as follows:
- 0-4 °dH: Very soft
- 4-8 °dH: Soft
- 8-12 °dH: Medium hard
- 12-18 °dH: Fairly hard
- 18-30 °dH: Hard
- From 30 °dH: Very hard
Geological influences on water quality
The water hardness of an area is mainly determined by the geological composition of the ground that the water passes through on its way. Rock layers such as granite or gneiss - so-called primary rocks - contain only a few water-soluble salts. The water absorbs correspondingly few minerals and therefore remains “soft”. However, it often contains free carbonic acid, which can have an aggressive chemical effect. The situation is different with sedimentary rocks such as limestone or dolomite, which are rich in soluble minerals. If water - especially water with a high carbon dioxide content - comes into contact with these rocks, large quantities of calcium and magnesium salts are dissolved.
The result is a sometimes strong regional fluctuation in water hardness. For example, the water hardness in the Bavarian Forest is around 4 °dH (very soft), while it is very high in Würzburg at 41 °dH.
The picture is similar in Austria: While the water in Lienz is still soft at 5 °dH, it reaches peak values of up to 43 °dH in Tulln.
Optimal water hardness for beer production
The best results for beer production can be achieved with a water hardness of 6°dH to 16°dH. In this range, the water contains a balanced concentration of minerals that optimally support the brewing process. Under certain conditions, however, the calcium and magnesium ions dissolved in the water can react with other water components and form insoluble compounds such as calcium carbonate (lime, CaCO₃). To ensure optimum conditions for the brewing process, the water must therefore be treated accordingly before brewing. This includes adding salts or removing excess lime using processes such as decarbonization, softening or reverse osmosis.
Water use in breweries
Water is used in breweries in various process steps with different quality requirements. Depending on the intended use, specific purity and composition requirements apply.
1. brewing water (brewhouse water)
Brewing water, which is used exclusively in the brewhouse, must be tasteless, odorless, clear and free of beer-damaging microorganisms. The chemical composition is essential, as dissolved salts such as calcium, magnesium or sulphate influence enzyme activity during mashing and later shape the taste of the beer. During the one-hour boiling process of the wort, around 5% of the water used evaporates, which increases the concentration of the remaining ingredients. The water quality must therefore be such that no undesirable aromas or turbidity occur.
2. cleaning water
For the cleaning of brewing equipment, pipelines and bottles, the water must be biologically flawless in order to avoid microbiological contamination. It must be neutral in taste and odor, as residues from the cleaning water could affect the beer. In modern breweries, the water is often additionally filtered or disinfected to ensure high hygiene standards.
3. cooling water
Various cooling processes are required in beer production - from cooling the ingredients and wort to fermentation and storage. To avoid deposits in the cooling units, the cooling water should also contain few scale-forming salts. Open systems such as cooling towers, on the other hand, require regular water treatment to prevent algae growth and microbial contamination.
4. Boiler feed water
Boiler feed water is used to generate steam for brewing and sterilization processes. To prevent scale formation, it should contain as few hardness constituents as possible, such as calcium and magnesium, as these lead to deposits at high temperatures. The water is therefore usually treated - for example by softening, demineralizing or adding phosphates. An excessive salt load can not only reduce the efficiency of steam boilers, but also lead to corrosion and increased energy consumption.
Waste water in the brewery
With the exception of the water that goes directly into the beer or evaporates, every drop of water ends up in the waste water. With a water consumption of around 6 hl per 1 hl of beer, around 3.7 l of waste water is produced per liter of beer.
Organic and chemical substances in brewery waste water
On its way through the production facilities, the water absorbs or dissolves a variety of different substances. The resulting wastewater is a complex mixture that contains both organic and chemical components:
- Organic residues such as beer and wort residues, trub, yeast
- Chemical residues from cleaning processes (alkaline/acidic water, disinfectants such as hydrogen peroxide or chlorine)
- Solids from bottle cleaning (paper fibers from labels, sludge, contaminants from label printing with heavy metals)
- Soluble substances such as label glue (usually starch glue), caustic soda, metal salts
- Operating materials such as oils, greases (from system lubrication) or belt lubricants from the bottle transport chain
Wastewater load and wastewater treatment plant capacity
The concentration of wastewater pollution increases continuously due to these contaminants. Multiplying the concentration of the contamination by its corresponding wastewater quantity gives the wastewater load. For example, a concentration of 10 milligrams per liter and a wastewater volume of 1,000 liters results in a load of 10 grams.
The wastewater load determines the required capacity of the wastewater treatment plants and has a direct influence on the level of wastewater charges, as the concentrations of BOD5 (biochemical oxygen demand in 5 days), COD (chemical oxygen demand), nitrogen (Nges) and phosphorus (Pges) determine the treatment intensity and the technical output.