Water is King!

Many of us have encountered both sides of the water spectrum at some point in our lives – the divide being between soft water and hard water. I remember the first time I moved away from my hometown of Leeds, in the North of England, and headed for the big city, London. Washing my hair was a wholly new experience – not a pleasant one! It just didn’t feel clean, no matter how much shampoo I applied. I put it down to it being a big city and so maybe water quality is relative to how many people are accessing it in a highly concentrated area. Later I grew wise to the fact that the North and South are worlds apart (in the pH level of their water…that is).

So what has this got to do with coffee, you might wonder? Well it is to draw attention to the fact that in most countries, the pH level of the water can vary quite greatly, depending on the region. The exact same coffee beans can produce different tasting results depending on where in the country they have been brewed. For this reason, the brewing potential of water is a pretty big deal and worthy of proper consideration. Here is an account of some of the reasoning behind why, we at Back To Black, recently switched from the Brita filter system to Reverse Osmosis. Buckle up!

It starts here: we are always striving to achieve ‘evenness’ in our coffee extraction and since water makes up more than 90% of our coffee beverage (92% of espresso and 98% of filter coffee), it made sense to double-down on our efforts in achieving ‘evenness’ in the core ingredient.

There are all kinds of Water filtration systems and each one has its own unique set of advantages and disadvantages. We were previously using the Brita system which is favoured by many coffee bars. Our results were pretty good with this but we are always trying to push our coffee to the next level. We saw the opportunity to do just that with the Reverse Osmosis filtration system.

The Reverse Osmosis procedure is two fold: first it is about taking out all of those dissolved compounds (water has many, from magnesium, calcium to Chloride and so forth) leaving us with over 99% purified water. This is done by pushing water through a semi-permeable membrane, separating the mineral content from the purified water content in two separate tanks. Then comes the magic: adding back in small quantities of Magnesium and Calcium to make for a more enhanced tasting cup of coffee. It is this balancing act that can take your coffee from flat to fantastic.

Let’s talk about that for a moment. What exactly does Magnesium and Calcium have to do with good tasting coffee? Without it (as in pure distilled water) we are having a very dull and flat coffee drinking experience. With the right amount of Magnesium and Calcium, we can add some vibrancy to the overall flavour.
Why? This is mostly to do with a concept called ‘Hardness’ (going back to the Hard water from the North versus the Soft water in London.. ).

Basically speaking, ‘hardness’ is to do with how much Total Dissolved Solids (TDS) are present in the water. 
This measurement (TDS is measured in Parts Per Million(ppm)) can tell us a lot about the water’s extraction capabilities, i.e, how much of the solid coffee can we dissolve into the resulting cuppa when brewing. To give you a bit of context, Tap Water, at its best, is bringing in a score of between 100-150ppm (however in Amsterdam it is closer to 225ppm) whereas purified, distilled water is as closer to 0ppm. Spring water holds the highest range of potential of ppm, reaching as high as 450ppm and as low as 50ppm.

We are managing to select how much TDS content to add back into our water which is used in our bars. We have found that the optimal range for us is between 85 – 130ppm. This (relatively) low TDS reading allows for a coffee taste of a pleasant clean acidity. This is where the roast profile at Back To Black shines at its best! We were previously using the Brita filter with a higher TDS (around 150ppm) which meant that it already has higher amounts of solids dissolved, diminishing the water’s capacity to absorb as much from the coffee. 

It has been only a matter of weeks since we started working with the RO technology. It is exciting to be able to manipulate the balance of TDS in real-time! Lot’s more to uncover in due course – we will keep you in the loop. What is your experience with water? Personally, I’m wondering how I can hook up the RO system to my shower for the perfect shampooing experience…just kidding!

References:

https://pubs.acs.org/doi/pdf/10.1021/jf501687c
https://www.raleighcoffeecompany.com/tds-and-coffee/
https://watercare.co.uk