Water filtration for coffee – specifically Cape Town Espresso

We understand that water filtration for espresso or most coffee brewing is complex. Requiring an extensive understanding of how water and coffee combine to make a great brew is well covered in the book Water for Coffee. Summarising the book is a challenge and we recommend if you are serious about water and coffee read it, probably twice. You can also read a summary and reaction here Water-Composition-for-Coffee

GH and KH in water

Water hardness is a measure of dissolved mineral content with in the water. There are two measures:

  • General hardness (GH) and
  • carbonate hardness (KH).

GH, or Total Hardness as it is sometimes called, is the total of the KH and any other dissolved minerals found.


Is the measure of the amount of Acid buffer capacity. Namely the amount of acid that needed to be added to a water sample to decrease pH to 4.3. Therefore it has a buffering the effect of adding acid to a water.

Ideal range

In the book, and in posts by the Specialty Coffee Association of America or Speciality Coffee Association of Europe there is an ideal range to aim for. While it is bit more complicated than this the idea is to have a GH range of between approximately 60 and 160 degrees and an alkalinity of between 40 and 70 degrees.

How is this applicable

Water in South Africa a quite soft. In fact in some cases it it too soft for coffee brewing. After asking a few people in coffee the basics are that filtration, removal of chlorine, and making sure that there is a good amount of Calcium and Magnesium.

Thanks to the Bean There team in Cape Town that suggested a combination of these Everpure cartridge:

4-CB5-S Cartridge:

  • Reduces chlorine taste and odor and other offensive contaminants that can adversely affect the taste of water and beverages
  • Reduces extra fine dirt and particles as small as 5 micron in size
  • Reduces limescale build-up that can cause excessive machine downtime and increased maintenance costs
  • Sanitary cartridge replacement is simple, quick and clean. Internal filter parts are never exposed to handling or contamination


7CC-BW Cartridge:

  • Protects equipment by reducing the corrosive tendencies of low TDS content waters
  • Improves electronic level control sensitivity by increasing water conductivity
  • Remineralization
  • Corrosion reduction

While there are other makes, this is the one that we know of.

If you are aware of other products, or have other recommendations please leave a comment. This is not cast in stone it is a recommendation.

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