For many of us, coffee is life. It’s the one thing that keeps us going through the day until the time it’s socially acceptable to turn to wine. But bad coffee is nothing to celebrate. A good cup of coffee can feel like a transcendent experience but a bad cup can turn your stomach in seconds.

What makes a good cup of coffee? That’s open for debate. Many would argue it’s the beans that make all the difference. That is, after all, where all of the flavour comes from. Or perhaps the brewing process itself? Few would argue, however, that the quality of the water has a significant impact on quality. This is odd, given that a cup of coffee is about 90% water. Even more, if you take yours without milk or cream!

How water affects your coffee

We might think nothing of filling the kettle or the coffee machine with water straight from the tap. After all, water is water, right? But while we might not be able to see it at a glance, the average cup of tap water will contain solubles and solids; from minerals and chemicals to traces of copper and iron from your pipes.

This all affects water quality. And if the water has a strange taste or smell, which can often happen when the water in your area is particularly “hard,” those unpleasant qualities will be passed on to your cup of coffee.

What is hard water?

Water hardness refers to the number of minerals in your water. While you might assume that minerals are a good thing (you buy “mineral” water from the supermarket after all) these are not necessarily desirable minerals.

Of course, many of these minerals will be sifted from the water during the boiling process but if you’re not careful, this can result in your kettles and coffee machines getting clogged up and becoming unusable.

It’s also worth noting that an element of carbonate hardness is always going to make for a better cup of coffee, as they are necessary to keep a stable pH balance and neutralise some of the acidity of the coffee. It’s all about finding that perfect balance.

The perfect balance

If your water is too hard then your coffee will have a flat and chalky texture and taste sour and heavy. If it’s too low in carbonate hardness, however, it will have an acidic and weak taste. There are, however, several ways of ensuring your water is the ideal hardness level for a good coffee.

Check your local source – Check with your local water plant and they should be able to tell you what the water you’re getting at home actually contains. If you’re using water from your own well, meanwhile, you’ll need to get a chemical analysis sorted.

Use a filter – Generic household filters can filter out larger particles in your water but many of the smaller particles will still get through. Still, it’s better than doing nothing and will remove most of the odours and impurities from your water.

Get a water softener – Installing a water softener in your kitchen is perhaps the ‘nuclear’ option but it is incredibly effective.

Note that many professional level coffee machines will have their own filters and softeners that will use processes such as reverse osmosis and activated carbon filtration to ensure the water is perfect for brewing. But for most of us, more subtle manipulation is often perfectly acceptable for a barista-style brew.