Have you ever used bottled water for brewing your morning cuppa? Although often underestimated, you could argue that water for coffee is at least as important, if not more important, then regularly debated brewing factors such as grind size or brew ratios.
Without going into too much detail for the science aspect, coffee tastes best when brewed with water including some minerals such as magnesium and calcium. However, too many can lead to coffee tasting flat and chalky and too few tasting sharp and sour.
Therefore, when cupping coffee for buying and quality control such as in Mercanta’s cupping laboratories, designing and monitoring water content correctly is an important factor.
In October last year, the Mercanta team was fortunate to host a very special coffee event at the Brazil embassy in London. The event was centred on the international coffee day, celebrating specialty coffee in Brazil.
UK roasteries with a single estate Brazil coffee were invited to submit a sample with the chance of winning prizes including a trip to Brazil. This was to promote the ever-improving quality of Brazilian specialty coffee. Rather than cupping the coffees, it was decided that we would brew the entrees using batch brewers and serving filter coffee, catering to a large number of attendees and making the event accessible for those not accustomed to a coffee cupping.
To make this work, we estimated we’d need 100 Litres of water – this would cover 100 people, trying 100ml of 10 different Brazilian coffees = 100ml x 10 coffees =1 litre x 100 people = 100 Litres.
As we were unable to transport so much water from our lab near Kingston, we had to test and buy the best-bottled water for the job. This meant hitting the supermarket in search of every bottled water we could find, bringing it back to the lab and testing to find the right one.
After a visit to Asda, I returned to Mercanta HQ with seven bottles of water, ready to test. These were:
Buxton, Evian, Nestle, Volvic, Smart Water, Asda Smart Price, Asda Still Natural (Cumbria)
After testing all seven bottles of waters, we were able to find some very interesting and useful results.
First up, the bad bad not good. We found that all of Evian, Buxton, Nestle and Asda smart price had such high mineral contents that they were ‘off the charts’ to consider for coffee. Interestingly, the cheapest water and perceived worst (Asda smart price) and the most expensive and perceived best (Evian), fell in the same category. If Evian may or may not be of ‘higher quality’ than Asda smart Price is a different conversation, what this tells us though is that for coffee, buying expensive water is not the way to go.
Next up, Smart Water.
Smart Water was found to have next to no Bicarbonate-Carbonate (HCO3-CO3). Having excess bicarbonates and carbonates, like Evian and Asda Smart Price, adds to the total solids content of water. This is often what leads to coffee tasting flat and chalky, as well as scale forming in kettles. Great news for kettles, bad news for coffee, as Smart Price was found to have too few bicarbonates, leaving our entrees potentially tasting sour.
Smart Water also had too high a concentration of metals such as calcium (CA2+), but in particular, magnesium. This proved a very interesting find, as high levels of Magnesium are often linked to brain health. In other words, we may have accidentally backed up smart waters claim that it does make you smart. Who would have guessed?
This meant of the seven tested, only two bottled waters fell anywhere near the ‘ideal brew zone’. These were Volvic and surprisingly, Asda’s own still water. From the graph below, you will see that although Volvics Metal concentration (magnesium and Calcium) was similar to Mercanta’s lab content, its high Bicarbonate concentrate pushed it out of our ideal brew zone.
This left Asda’s own brand still water. By almost some miracle, not only did we find suitable water, but one with near-perfect results (success!). This means, if you were ever looking to improve your homebrew, Asda’s own still water is the way forward, however, don’t stop reading here.
Although branded the same, ASDA’s own still water is bottled at 2 different plants (sneaky Asda). Look closely at the labels and you will see some our sourced in Staffordshire and some in Cumbria. Buying the Staffordshire bottle means you may as well have bought Evian or Asda Smart price and you may as well put your pour-over kettle and V60 in the bin as no nice coffee will be brewed. If you manage to find the bottled in Cumbria, you’ll be drinking floral-fruity coffee to your end of days.