Last Updated: March  3, 2021

What is the best water for coffee?

How much should you really care about the quality of the water you use to brew your
coffee? The answer to this question depends on the type of coffee drinker you are.


If you mainly enjoy drinking coffee for the dopamine rush that you get from your caffeine
fix, then you can pretty much use any water to make the coffee.
But if you enjoy experiencing a real explosion of flavour with each cup of coffee, then
the water you use to make it can make a big difference. Read on to find out why:

best water type for coffee

Why is choosing the best water for coffee important?

The water you use will affect your coffee in two main ways.
First of all the pH of the water will affect the flavour of your coffee, for example by making it taste more bitter. And secondly, if you use a coffee machine to make your coffee, the minerals in the water can cause corrosion or limescale build up in your machine. So if the coffee you make is not quite the same as the one you buy from your local coffee shop, the mineral content of the water is probably to blame.

Which minerals are important for coffee?

Two main minerals in water can affect the flavour of your coffee - calcium & magnesium. Both minerals help your coffee get extracted in different ways.
Calcium levels in water should generally be between 17-85 mg/L and magnesium should generally be at about 0-60 mg/L, depending on which recipe you want to follow (Rao/Perger, Barista Hussle etc.). The total dissolved solids (TDS) in your water should be no higher than 150 mg/L but by adjusting levels of calcium and magnesium within this, you can change the way your coffee tastes.
Calcium and magnesium bind to the different elements and compounds in your coffee, which changes the way it tastes. Calcium will give a heavier, rounder, creamier flavour to your drink, while magnesium reacts with compounds like citric acid to produce coffee with a brighter, sweeter flavour.
And the total alkalinity of the water helps to keep the pH constant (avoids pH change) and act as a buffer. Without this, the magnesium and calcium levels wouldn’t have so much effect on flavour. So now you know a summary of the science behind your coffee’s flavour, let’s take a look at which is the best water for coffee.

Tap Water

tap water for coffee brewing

Using the water that comes straight out of your tap is the easiest option for your morning cup of coffee, but does it make a good cup?
 

Purity - 1/5
The purity of tap water varies depending on your location and water pipes, so we’ve
given it a low score.

 

Mineral content - 3/5
Tap water generally has too much calcium, too little magnesium and is too alkaline to
give a good cup of coffee. But the bigger problem is the inconsistency of mineral levels.
Each cup can have a different mineral composition, so it’s hard to brew the perfect cup
of coffee.

 

Availability - 5/5
Nothing is easier than turning on the tap so this gets a high score from us.

Filtered water (e.g. Brita water jug)

Lots of us have a water filter jug in our fridge, but does filtering water make a better cup of coffee?


Purity - 3/5
The carbon and resin based filters in these jugs are great at removing elements like chlorine, but don’t have much effect on the mineral levels. A few models will take TDS down to zero but don’t remove other impurities.

Mineral content - 2/5
The results vary depending on which jug you used, so you’ll need to test different water sources and different filters to find your ideal water for coffee. And that’s not very practical!


Availability - 3/5
Filter jugs are readily available to buy, but you’ll need to change the filter regularly which increases the cost.

Bottled water

bottled water for coffee brewing

Bottled water is very popular these days, so could this be the best water to make your cup of coffee?


Purity - 4/5
Bottled water loses a mark on purity due to recent concerns about microplastics in the water, however these won’t have any impact on the flavour of your coffee.

 

Mineral content - 4/5
Mineral levels in bottled water tend to be pretty high compared to the optimal levels for coffee extraction, which will affect the way your drink tastes.

 

Availability - 2/5
You can buy your bottled water online or at the grocery store, which sounds simple until you run out at the most inconvenient time!

Pure Water

Pure water is water that has had its impurities removed through distillation or reverse osmosis.


Purity - 5/5
This is about as pure water as you can find. But if it’s stored in a plastic bottle for too long, it can start to break down the plastic, which can affect the smell and taste of the water.


Mineral content - 1/5

The very low mineral levels in pure water will not create a delicious cup of coffee. You’ll end up with a flat tasting coffee as the distinct flavours of the beans will not be extracted. Pure water can also cause corrosion on the metal parts of your coffee machine, such as the heating element.

 

Availability - 3/5
You can buy pure water from a store or make it yourself using a reverse osmosis or distillation unit.

Pure water + concentrate

pure water with minerals for coffee brewing

This type of water has been purified using distillation or reverse osmosis. Minerals are then added back into the water by using mineral sachets popularised by brands like Third Wave Water or Perfect Water for Coffee

Purity - 5/5
This is very pure water but needs to be stored carefully to avoid affecting the flavour.


Mineral content - 4/5
Using a popular mineral concentrate such as Third Wave Water (TWW) will produce water that has been optimised for coffee extraction. Each capsule gives the following levels when added to distilled water:
○ Magnesium 58.65 mg/L
○ Calcium 19.02 mg/L
○ Alkalinity: Unknown

Availability - 3/5
As well as buying or purifying the water, you’ll need to buy the mineral concentrate. If you have a Reverse Osmosis or Home Distillation unit at home, it will also need regular maintenance. All of this makes it less convenient than some of the other water sources.

Conclusion

Ultimately the best water for coffee is a matter of personal preference. You need to weigh up the benefits of a great tasting cup of coffee versus the hassle of sourcing the ideal water to make it. Only you can decide how far you are willing to go for the ‘perfect’ cup of coffee.

By Alex written on the 15 Sep. 2021

pure water for coffee brewing
filtered water for coffee brewing
Calcium magnesium and total alkalinity