Is Hard or Soft Water Best for Brewing Beer?

The average beer drinker might not think much about the water used to create their favorite beverage. But brewers know that the mineral content of water makes a huge difference to how beer looks, tastes, smells and feels in the mouth.

In fact, water can be considered just as essential as hops and yeast when it comes to beer composition. The use of hard or soft water can result in different outcomes and completely different types of beer.

Here’s a look at how hard and soft water affects the beer brewing process, why it is the secret ingredient behind some of the most iconic traditional beers.

What’s the difference between hard and soft water?

Water hardness of softness is a measure of its mineral content. Specifically, it refers to the presence of naturally occurring salts like calcium, sodium and magnesium.

Hard water

One of the most important variables in brewing is the hardness of the water being used. Hard water is water containing high amounts of certain dissolved minerals, particularly magnesium, calcium, manganese and zinc.

These minerals usually enter water early on in the water cycle, when water is trapped underground and may be subject to intense pressures. If groundwater moves through bedrock that’s full of magnesium or calcium-rich soil, the minerals are liable to dissolve in water.

For most people, water hardness is discovered by the taste and feel of their tap supply, as well as the presence of scale appearing in their kettles and dishwashers. However, there is also a scientific definition of water hardness, which is a level of calcium carbonate higher than 121mg per liter of water tested.

Soft water

You’d be forgiven for thinking that the term soft water refers to water with low levels of dissolved minerals, but actually, soft water doesn’t necessarily have a lower mineral content. While it’s true that soft water contains far less calcium and magnesium than hard water, it may contain higher levels of other minerals, like sodium and potassium.

Rainwater is low in groundwater minerals and is therefore inherently soft. Tap supplies that don’t spend lots of time passing through bedrock is also likely to be softer than deep groundwater.

Artificial water softening is also a common practice, and many people living in areas with hard water will have a cost-saving water softener installed in their home plumbing. These devices work by sending water through a resin filled with negatively charged, sodium and potassium ions.

Because the hard water ions, calcium and magnesium, are positively charged, an ion exchange occurs as water passes through the resin. This turns hard water filled with groundwater minerals into soft water containing salts.

How does water hardness affect beer?

One of the most critical things brewers need to control when making beer is acidity. The reason that levels of acidity are closely regulated is that the enzymes used in brewing are only active in a narrow acidity window—between around 5.2 and 5.5 on the pH scale.

When water contains high levels of hard or soft minerals, its acidity changes. Very hard water that contains lots of calcium and other alkaline minerals can have a pH level of around 8. Very soft water, on the other hand, might have a pH level of around 6.

As a result, the introduction of very hard water or soft water into the brewing process can change the way that enzymes react. Levels of water hardness/acidity is one of the primary reasons for the notably different characteristics of traditional beers from eight European cities.

When is hard water best for brewing?

More alkaline hard water containing lots of calcium and magnesium is generally considered to create hoppier flavors and darker profiles in beer. Beer made from hard water is also more likely to have a rich mouthfeel.

These associations can be seen in the traditional beers of hard water regions. Porters, stouts, and heavy larger like dunkels are often found in cities like Dublin, Munich and Dortmund, which are known for their hard water.

When is soft water best for brewing?

More acidic softer water with a lower pH is generally considered optimal for making lighter, crisper beer. IPAs and clean lagers with rounded palettes are often made with soft water low in calcium.

For example, the famously crisp and lightly colored Czech pilsner is traditionally made from soft water low in bicarbonates. Today, most breweries artificially control the ph level of water using boiling or the addition of distilled water. This allows authentic beers like pilsners to be brewed worldwide.

Summary

Like any natural substance, water isn’t the same in every region or source, and different levels of dissolved minerals in water can have a dramatic effect on the brewing process. Hard water rich in calcium and magnesium often results in dark, rich beer, while softer water lends itself to cleaner, more bitter ales.

Today’s brewers can artificially alter the composition of the water they use, however, this adds lots of variables and complexity to the brewing process.

In fact, water hardness is just one water issue brewers need to deal with. Many parts of modern water treatment, such as chlorination, can affect the brewing process and also need to be accounted for