Most brewers can name three key ingredients in beer brewing: malt, yeast and hops. But what about the more mysterious fourth ingredient that is often overlooked? Yes, we’re talking about water. Water is important as it makes up more than 90% off your beer. It’s often said that the difference between a great beer and an amazing beer lies in the chemistry of your brewing water and how this matches the beer you are brewing.

In this article, our brewing experts talk you through water chemistry in beer brewing. We look at water sources, the different ions present in water, and the effect they have on your beer. Water may seem like a rather straightforward ingredient. However, in reality, it is made up of complex chemicals like salts, ions and minerals that can be evaluated and modified during the brewing process. 

The general rule of thumb for beginner brewers is: if your water is drinkable and tastes good, it is suitable for brewing. There are, however, some water sources to be aware of.

Municipal water sources

Most municipal water sources are treated with chlorine or chloramines to stop the growth of bacteria as the water travels between the treatment plant and your house. This treatment can harm the growth and health of your yeast.

Well and surface water

Well and surface waters can contain lots of metallic ions, like iron, which can add a metallic taste to your beer. 

Store-bought water

For the most part, store-bought water is the safest option and is also very consistent.

Top tip: Avoid volcanic waters. These contain lots of minerals and salts that can play havoc with your beer. 


If you’ve brewed a batch of beer that tastes a little off, here are some suggestions for areas you can improve on.

My beer tastes like band-aids, medicinal, disinfectant

This is most commonly caused by chlorine and chloramines that have turned into chlorophenols by the yeast. To remove chlorine and chloramines from your water, use a carbon filter, Campden tablets, or boil the water for 7 mins before use. To remove chlorine, let the water sit for a while before use so that the chlorine can evaporate.

My beer tastes like pennies, blood or metallic

This is most commonly caused by iron or other metals present in the water source. These can be removed by chemical treatment or by filtering your water. 

Only my pale beers or dark beers taste good

Your water has a mineral ratio that will be suitable for light or dark beers. Keep brewing the style that works for you, or look at a new water source to improve the other style.


When you are ready to transform your great beer to an amazing beer, its time to start looking at the chemistry and chemical make up of your water. 

pH levels

pH levels affect every step of the brewing process and will need to fall between specific ranges to optimise the brewing environment:

  • In the mash, the pH should be between 5.2 and 5.6. This is the optimum range for the enzymes in your mash to function.
  • During the boil, the pH drops a little bit due to the reactions of the sugars and added hops.
  • As the yeast produces alcohol during fermentation, the pH of the wort lowers once again to around 4-4.5. This helps protect the beer against spoilage organisms. 
  • Note: If you’re making a sour beer, the pH can be as low as 2 in some extreme sour beers. 

pH can be adjusted at any stage in the brewing process with acids, bases, buggers and salts. To calculate pH adjustments, use the Grainfather water calculator to adjust your pH based on source water pH, the grains that are in your beer and the style of the beer you are brewing. 

Water Ions

After the pH is sorted, look more specifically at the ions present in the brewing water. These will be present at different levels depending on your source water and each ion will ultimately play a role in the end taste of your beer, either directly or by altering the perception of maltiness or hop character.