Let’s get technical
Water hardness is determined by the amount of total dissolved soilds (TDS), which is measured in parts per million (ppm). The Specialty Coffee Association recommends 150ppm as the optimum TDS level for brewing water for coffee. However, anywhere between 75ppm and 250ppm is considered within the acceptable range.
Water hardness can vary dramatically in the UK, even within small areas. The UK Water Hardness map can give you a rough idea of the water hardness in your area, however this is only an area average, and hardness can vary within these areas. In Lancashire, for example, water type varies from town to town with pockets of both soft and hard water sometimes in close proximity. As such we would always recommend testing the water before specifying any water treatment equipment.
How does your water shape up?
Testing your water is simple, and there are many low cost water test kits available. Once you know how hard your incoming water is, you can then calculate the capacity of the treatment system you’ll need.
Shop water test kits here.
The Right Stuff
Unfortunately there are a few other things to consider in order to achieve the perfect water for brewing coffee.
The minerals that cause hard water (calcium and magnesium) aren’t the only dissolved solids that might play havoc with your coffee. Certain sites in the UK receive mains water which contains chlorides and sulphates and these can impart a sour or bitter flavour in brewed coffee. Reverse osmosis removes these minerals, while for lower capacity sites ‘problem solving’ filter cartridges such as the Claris Prime have been developed to combat this very issue.