Manipulating water to improve the effectiveness of coffee extraction, a popular practice dubbed as ‘designer water’ within the top tier barista community, is likely to be futile, found a new study released by Seven Miles Coffee Roasters.

Conducted by Seven Miles’ resident chemical scientist Dr Adam Carr in partnership with UNSW, the study found Sydney tap water treatment targets ideal for espresso extraction with minimal treatment required to get the most out of espresso.

“There’s a lot of noise in the coffee industry about how water quality affects espresso flavour, but few people have quantified what the changes actually are. This study examined how changes in pH, hardness and total dissolved solids affected the concentration of five flavour compounds, which generated ‘bitter’, ‘nutty’, ‘chocolate’, ‘caramel’, and ‘fruity’ flavours,” said Dr Carr.

The greatest contributing factor to flavour was found to be ‘hard’ versus ‘soft’ water, which refers to the quantity of magnesium, calcium and other minerals added. Soft water (featuring low levels) generated a flat, lifeless taste while hard water (with high minerality) was optimum for depth and complexity of flavour.

However, the trouble with hard water is that it can lead to the build-up of scale (mineral deposits) inside equipment and machinery, depleting the lifespan of the machine. Thankfully the analysis found that flavour extraction peaked at 60 parts per million calcium carbonate, while conditions for scale development sat around the 90 parts per million mark, meaning baristas could still have the benefits of hard water without compromising their equipment.

“We’ve now established a benchmark for optimum water quality for espresso, which means we can go out into the field and troubleshoot water quality across Australia to help cafes identify if there are any water condition issues affecting the flavour of their coffee,” Carr said.

Now equipped with a reliable indicator of water quality, the ‘designer water’ trend involving stripping water down and then building it back up by adding sodium salts and other total dissolved solids may diminish.

“The problem with stripping down water is that you remove a lot of its good qualities, and our analysis has found that altering the total dissolved solids had little impact on flavour. It’s a popular practice in barista competitions for contestants to bring their own ‘designer’ water with added salts. Why bother when Sydney Water does the hard yards for you?” said Dr Carr. Instead, he recommends simply using a carbon block filter to help filter local impurities that may exist within local water pipelines.

This study was developed by the Seven Miles Coffee Science and Education Centre (CSEC), a new hub for pushing the boundaries in experimentation by leading scientists and industry professionals. This study was conducted using Sydney tap water and studies across Australia will follow later this year.

For more information, please visit https://www.sevenmiles.com.au/coffee-science-education-centre/