Manipulating water for coffee

We recently wrote an article for Taste Cumbria magazine focusing on the component which makes up around 90% of your daily cup of coffee: water. This blog post is intended to build on the content of that article, for those who want to ‘dive a little deeper’ into the impact of water on your coffee.

The starting point for understanding the impact of water on your coffee is to gain an insight into the type of water you currently have. The easiest way to do this is via the website of your local water company. A quick visit to the website of United Utilities, reveals a section entitled ‘Drinking Water Quality’. You can simply type in your postcode to reveal data about the water in your taps. The examples below relate to the water composition at our roastery in Threlkeld and it is no surprise to find out that we have soft water. We should expect it to increase the acidity in our coffee, making it difficult to discriminate flavours clearly. In some instances the coffee might taste sour, depending on the style of roast.

Water quality.jpeg

The composition of the water across our region varies greatly. A quick postcode search reveals the following snapshot:

Carlisle has moderately soft water

Penrith has slightly hard water

Kendal has soft water

Barrow has moderately hard water

Each of these waters will have a slightly different impact on coffee, broadly along the following lines:

If you are drinking coffee in Carlisle, the hardness level falls within Speciality Coffee Association (SCA) acceptable limits1.

The water in Penrith falls out of the SCA acceptable limits, but not by a huge amount. Coffee will likely taste heavier and darker notes might be more obvious than in Carlisle.

The water in Kendal falls out of the acceptable standards but at the other end. It is likely to make the coffee taste weak, flavours might be hard to discriminate and some coffees might taste sour or sharp (coffees from Africa spring to mind here).

Barrow water has the most minerals, taking it further out of the acceptable limits than in Penrith. Coffee will taste heavier and more over extracted in this water. There might also be noticeable scale on kettles.

Some solutions

Each of these waters needs a slightly different approach (aside from Carlisle). The one solution which works for all waters is to use bottled water instead, and in particular Volvic. This is not a particularly environmentally friendly approach, and I do not suggest you adopt this as a long term solution, but it will allow you to explore whether a different water is going to have a positive impact on your coffee. Buy a bottle of Volvic, use it to make your coffee (try to keep to your normal routine) and if you experience a positive result then perhaps it is worth trying one of the following:

For hard water

The simple solution is to use a Brita style filter jug which will remove some of the minerals from the water. This approach is particularly useful in Barrow, or regions which have a similar hardness level but would also work in slightly hard areas. Another approach for ‘slightly hard’ water is to use a mix Brita filtered water 50:50 with tap water – the impact of this will be to slightly reduce the overall mineral content.

For soft water

2.7 L - Aubergine Jug GHKThere are now Brita style filter jugs which actually remineralise water using Magnesium.   While these do not lift the mineral content into the acceptable standard, they do have a positive impact on the water and produce an overall better cup of coffee. They are also a more environmentally friendly solution than bottled water.  We have these available on our website.

The other approach, which mimics what we do at our Roastery, is to physically remineralise your water by adding some simple household chemicals. We’ve been remineralising our water at the roastery for a long time but use 25 litre barrels, adding a couple of grams of the chemicals at a time. This isn’t practical at a domestic level but we came across an idea on Barista Hustle which we have adapted slightly to suit our local soft water.

Start by mixing 500ml tap water with 8g of epsom salts and 4g of bicarbonate of soda. Make sure you mix until the crystals have been dissolved. This is your concentrate which you can store in a suitable container (it’s a neat way of reusing that empty Volvic bottle you used earlier!)

Every time you need to create a batch of remineralised water, simply mix half a teaspoon of your concentrate with 500ml of tap water. It’s a really simple way to create remineralised water which pretty much falls within the SCA acceptable standards.

Remember this remineralising recipe has been produced to work with the existing soft water in our region.  If you live in hard water areas I advise either the earlier solutions on this page, or to read the Barista Hustle article in more depth, particularly version 2.

We’re always happy to hear you comments and questions, and will endeavour to answer them promptly.

  1. The Speciality Coffee Association have determined acceptable standards for water used to brew coffee, based upon the work of others, such as Hendon & Colonna-Dashwood in their book ‘Water for Coffee’.

4 Comments Add yours

  1. Peter Hackney says:

    Hi Gareth. I thought, when we spoke in the Moon & Sixpence, that it was Mg and K salts that was used to engineer our tap water for coffee. I remember you said Epsom salts, but bicarbonate of soda doesn’t contain K. Have I got this wrong? Thanks, Peter.

    1. Peter we use potassium to increase the alkalinity at the Roastery but sodium bicarb achieves the same effect but is more readily available, hence suggesting it in the article.

  2. Peter Hackney says:

    Many thanks for this explanation Gareth. Will now try this at home and let you know if I can raise my coffee to approach the standard at the Moon & Sixpence. Wife thinks I’m getting OTT! Peter.

    1. No such thing as OTT when it comes to coffee 😉

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