What water should you use for coffee?

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Water makes up 98.5% of your cup of coffee, so you’ll want to use the right water to brew the perfect cup.

The type of water you use will affect the way your coffee tastes, however, you don’t necessarily need to use bottled or filtered water for exceptional coffee.

Wondering where to start in making sure you’ve got the right water for brewing? Below we take a deep dive into this often overlooked topic and answer all your coffee water-related questions.

What is water?

Water contains two atoms of hydrogen and one atom of oxygen. That’s why it is referred to as H2O. There are billions of water molecules in every drop of water.

Although water is clear in its appearance, it can have a tremendous amount of contaminants in it.

Even though water covers most of our planet, it is not always clean enough for people to drink. Water treatment is the method of cleaning water so that it is safe for people to drink.

Disinfection with chlorine or other chemicals is a standard part of treatment to kill any germs in the water.

In addition to the byproducts from treatment, other dangerous contaminants can also remain in our tap water after treatment.

These include aluminium, copper, iron, and lead.

It’s also worth keeping in mind that even if your drinking water is safe, it can contain bad tastes or odours. This is not good news for coffee brewing.

Hard and soft water

Hardness is a measure of the mineral content in water, and these minerals can significantly affect your coffee’s flavour.

Of all the different minerals and salt properties in water used for coffee, magnesium and calcium have the highest extraction properties.

Because magnesium and calcium help to extract taste, they should be present in water for brewing coffee. However, too much of them can be harmful.

We, therefore, don’t want very hard, or very soft, water, but a delicate balance between the two.

This is where things start to get pretty technical. However, there are some great resources out there if you want to dive deeper into the topics of Total Hardness and Carbonate Hardness, pH levels and alkalinity.

This post by the Barista Institute is fairly comprehensive, as is this one by Seven Miles and this one by Barista Hustle.

If you want to dive deeper still, check out the book “Water For Coffee” by barista champion Maxwell Colonna-Dashwood and chemist Christopher Hendon.

Their conclusion, which was groundbreaking at the time, was that the most important thing about a water’s ability to brew good coffee is the ratio between two kinds of hardness—total hardness and carbonate hardness.

Total dissolved solids (TDS)

TDS tells us the amount of soluble solids in a liquid.

This includes everything, from things like organic matter and alcohols, as well as calcium and magnesium.

The Specialty Coffee Association of America (SCAA) recommends that the proper TDS for water to brew coffee is between 75 and 250 parts per million, with the target being 150 ppm.

The total dissolved solids in your coffee is a measure of extraction. It also relates to how many dissolved solids there are in the water.

TDS is a popular measurement for baristas and home brewers because it helps them measure and control extraction. This means they can brew consistently balanced cups with depth and sweetness.

However, TDS is not without its critics.

For example, in the Seven Miles study referenced earlier, they found that “adding salt to increase TDS made no difference to extracted flavours.”

However, it remains a popular reference amongst coffee brewers, due in no small part to the ease of measurement. Refractometers, the tools used to measure TDS, are reasonably easy to come by and easy to use.

A refractometer measures how much light bends as it moves from air to liquid. The TDS measurement allows you to calculate the extraction yield, by comparing it to an index.

What kind of water should I use for coffee?

Good water can be hard to come by if you’re on a municipal system with lots of added chemicals, or if you live in an area with hard water.

In particular, if your tap water tastes or smells funky, you’ll need to find a way to sort that out.

Below, we cover some of the common options coffee lovers can use to obtain better water for brewing.

Water filters

Filtration can be an effective way to get water suitable for brewing coffee.

Filtering removes impurities from water, leaving it less processed than regular tap water.

Importantly, however, it doesn’t completely strip the water of all minerals that are important for efficiently extracting flavourful coffee from your coffee beans.

SEE: The Best Water Filters For Coffee Machines

Distilled Water / Reverse Osmosis water

If you have hard or soft tap water, you may have been tempted by distillation.

Distillation and reverse osmosis systems may seem like an easy solution, however, they come with their own challenges.

Not only can they require a long and complicated process, but they also strip out many of the minerals that we actually want in small quantities to make a great cup of coffee.

You do have options to you here, though. You can either distil in a way that rebalances the water, or you can add the minerals back in at the end.

Can you use bottled water to make coffee?

Bottled water is free of chlorine and generally tastes better than tap water.

It’s not, however, always going to be the best option for brewing coffee.

Many brands of bottled water is either extremely hard or have no minerals whatsoever.

As we’ve discussed, this poses problems for optimal extraction from ground coffee beans.

A small amount of minerals do make coffee taste better, so if your bottled water claims to be soft, you might want to try another brand.

Other options

Peak Water Jug

The Peak Water jug was designed by the people who brought us the book ‘Water for Coffee’, as discussed earlier.

The Peak Water jug is an easy and effective way to bring high-quality water for all types of coffee.

By using a resin-based filtration cartridge system, the water reaches the right level of minerals to help bring out the desired tastes when brewing.

The filter’s simple design is user-friendly, allowing users to adjust the filters settings from soft to hard water.

This helps to remove sediment and chlorine that can lead to scale build-up in espresso machines and water kettles.

Third Wave Water

Third Wave Water capsules are designed to exactly match the Speciality Coffee Association (SCA) water quality standards, ensuring that you have perfectly balanced water for making coffee.

Here’s how to make your own water: just add a capsule of minerals to 4 litres of distilled water in a jug, shake, then use like normal.

Water Temperature

To make a good cup of coffee, start with fresh cold water.

Don’t use hot tap water because it’s probably not fresh, and might have odd tastes or odours.

The National Coffee Association recommends that water used in coffee brewing has a temperature between 91°c and 96°c, and this range works across all brewing methods.

The boiling point of water is 100°c, so this is a little below boiling.