Craft Brewing 101: The Way of the Water

Beer is often described through hops, malt and yeast. But before any of those come into play, there is water. Water makes up around 90–95 percent of a beer. It’s not just the starting point. It’s the environment everything else has to work within.

At To Øl City, our brewing water is purified through reverse osmosis. This process removes minerals and particles, leaving us with a completely neutral base.

Think of it as a blank canvas.

From there, we rebuild the water profile from scratch, adding specific minerals to suit the beer we’re brewing. This gives us full control and allows us to shape the water to support both flavour and fermentation.

Why minerals matter

Water chemistry plays a quiet but crucial role in brewing.

Minerals don’t just influence taste. They affect how yeast performs, how a beer feels in the mouth, and how balanced it appears.

Yeast relies on certain minerals, such as calcium and magnesium to thrive during fermentation. Even small changes can influence fermentation speed, clarity, mouthfeel and overall balance.

Some minerals push a beer in a specific direction:

Sulfate-rich water can make a beer taste drier and sharpen hop bitterness.

Chloride-rich water tends to create a softer, rounder mouthfeel and highlight malt sweetness.

By adjusting the mineral profile, brewers can subtly guide how a beer expresses itself.

Water and beer styles

Historically, brewers didn’t have the option to rebuild their water. They brewed with what came out of the ground.

That’s why many classic beer styles are closely tied to geography. The local water helped define their character.
Brewers still look to these places for inspiration. When developing a beer, the mineral profile often starts with the water of the city where the style originated. It’s no coincidence that hop-forward British pale ales emerged in regions with naturally higher sulfate levels.

Water shaped the style long before anyone knew why.

More than an ingredient

Our brewery sits above Denmark’s newest registered natural spring, Brokilde.

One day, we hope to use it in its natural form for spring water, sodas or new beverages. But since it’s not ideal for all beer styles, the beers get the RO version. It gives us flexibility and consistency across everything from crisp lagers to hop-forward ales.

In brewing, water is not only part of the beer itself. It’s also used for cleaning, steam generation and sterilisation.

At To Øl City, we operate our own water treatment plant, ensuring that all water used in production is cleaned thoroughly before being released back into nature.

Water flows through every part of the process. What comes in clean should leave clean too.