Last Updated: 16th September 2021
It is easy to forget that coffee is mostly made up of water, and it is the biggest ingredient by weight. In an espresso alone, around 85% of the drink is water, and that is considerably more in taller coffees.
But how many of you out there just fill the kettle straight out of the tap, or use unfiltered water in your machine? With over 60% of the country having hard or very hard water, this could cause problems for all sorts of reasons, from changing the taste of your coffee to damaging the internal workings of your machine.
However, minerals aren’t always a really bad thing…
Hard water contains a lot more mineral content deposits than filtered, or soft, water. They are formed when water is naturally flowing through deposits of limestone, chalk or gypsum.
Whether your water is naturally hard or soft straight out of the tap all depends on geography, unfortunately. In areas mostly made up from non-porous surfaces such as granite, the water simply runs off surfaces rather than permeating it, meaning it is softer.
Scotland, Northern Ireland, most of the North of England and the South West has soft water, while a lot of the Midlands and West of England has hard water. Bad news if you are in the East and South East though – your water is likely to be very hard. You will probably realise the difference when washing dishes, washing your hair or even just the general taste, look and feel of the water.
According to research, water hardness levels can make or break a cup of coffee. If you read below, you will actually see that not all mineral deposits are bad for the taste and extraction method, but they should generally be kept at small doses, which can make the issue of filtering more difficult.
But one argument for filtering the water is that it means a more consistent taste. Water hardness can actually change ever so slightly from day to day, depending on how much it has rained for instance, so that also means that no two cups of coffee may ever taste the same. Thus, water can drastically affect how well you can taste the different flavours your coffee naturally inherits.
Actually, no. These are some of the most common minerals found in water in the UK, and the effect they will have on your hot beverage:
Mineral deposits can start to build up in your coffee machine a lot quicker than you’d imagine. Some of the compounds are ‘sticky’, so will attach themselves to any surface they pass through, especially if this is metallic.
Think about the way your coffee machine works and how the water ends up in your cup; you fill a tank, the water is heated, it travels through the machine to be passed over the grounds and is then dispensed through the water head.
Even with manual forms of coffee preparation, the water touches a lot of parts of the unit and travels through tubes, through filters and pourers.
If you have a warranty or guarantee on your coffee machine, then there is even worse news if you don’t keep on top of filtering. Any problems caused by mineral build up are often not covered, as part of the warranty will involve regular maintenance and cleaning. This includes descaling. You have been warned…
Confusing, isn’t it?
Hard water is generally bad (especially for your machine), but soft water will mean a harder job extracting the flavours. Some minerals are really bad for coffee, but some are fine in small doses. So how do you make your water exactly right for coffee?
The simple answer is that not all water filters are the same. There are many available, including ones that take away all of the undesirable additions listed above while leaving small traces of calcium and magnesium. Activated carbon/charcoal options can be good, as they fully clean the water before putting minerals back in.
Test your water beforehand to see what is present, as there may not be anything there which can have a negative effect. If you live in a very hard water area though, it is probably worth it.
Filtering can be better than buying bottled water, as not only are you not using all that plastic, but bottled water may not contain the minerals required. It is used to drink and not just make coffee with, after all. Depending on the results of your test, you can: