What is the Best Type of Water for Coffee?

What’s the best water for coffee? Does it even matter? Yes! Find out why.



Brita water filter with Chemex, white bowl and glass mason jar



You know your coffee to a T. Grind size? You’re on it. Brewing? You could do it in your sleep.


    But what about the water?     


Water is key when it comes to coffee. It’s not a case of one water fits all. Some types are great for coffee, while others will make your lovely cup taste flat and dull – even if you’re acing that brew method.

Using distilled water for coffee? Stop! You’re making your mug sad. So come with us to Hydration Station as we find the best type of water for coffee.




Water: why is it important?

A cup of filter coffee is 90 percent water. This means it’s got even more water than you. So it deserves attention!

The type of water you choose – tap, filtered, distilled – can have a big impact on the flavour of your coffee. Just try brewing a cup with tap water and then with bottled mineral water – we think you’ll taste the difference!

Many speciality coffee shops invest in special water-treatment systems to filter their water and set in specific mineral levels and acidity values. We guess one of these pricey machines isn’t on your Christmas list, but don’t worry – we’ve got everything you need to know to help you choose the best water for your coffee!


Pouring water from swan neck kettle into coffee cupping dish sitting beside trays of coffee beans




The science bit

Grab your mad scientist wig (what do you mean you don’t have one?!), because we’re going to take a look at some water chemistry.

A water molecule contains two hydrogen atoms and one oxygen atom. The hydrogen atoms sit on one side and have a positive charge, while the little oxygen atom sits on the other side with its negative charge.

This polar arrangement (a slightly positive end and a slightly negative end) makes them attractive to other molecules and is why other substances dissolve in water.

Coffee amongst them! When heated, water causes a chemical reaction that extracts flavour from the coffee grounds. Flavour compounds extract at different rates:

  • Acids extract first
  • Then sugars and sweet flavours
  • Caffeine compounds and bitter flavours extract last

This is why coffee tastes bitter if you brew for too long!

And don’t forget – the water temperature is major factor, too!


Coffee in a yellow mug at Two Chimps roastery



What is the best water for coffee?

There are two main things to think about when considering the best type of water for coffee:


Mineral content



Remember pH values and litmus paper from school? It’s gonna come in handy here!

Alkalinity describes the ability of water to neutralise acids and maintain a fairly neutral pH. We also refer to this as its buffering capacity. You might hear it described as ‘calcium hardness’, too. The number of bicarbonates (hydrogen carbonate, HCO3) a water contains is the main factor affecting alkalinity.

Coffee is acidic and so requires some alkalinity to ‘buffer’ its pH and create a lovely, balanced flavour.

Too little alkalinity and the acids in your coffee will have a rave. And the final cup? It’ll taste sour.


Pouring water into a Hario v60 using a swan neck kettle


Water is generally neutral (it has a pH of 7), but it can also be slightly acidic or alkaline. Did you know that regular drinking water in Europe can have pHs ranging from 6.5 to 9.5?

So, to achieve a harmonious cup, we need some alkalinity but not too much. This makes a neutral pH perfect and means that the best water pH for coffee is 7.0! But anywhere in the 6.5 – 7.5 range will do just nicely.


Water filter beside cold brew coffee maker and white coffee cupping bowl


Mineral ions

You need vitamins and minerals, and so does your joe! Well, minerals at least.

We find lots of mineral ions in drinking water, like calcium, magnesium, sodium and potassium. They’re really important for coffee extraction due to their positive charge.

Calcium and magnesium are the guys we really love here because they bond well with other substances. This makes them champion extractors of coffee flavour (mostly negatively charged).

It’s not about more more more minerals, though. The best type of water will contain just the right amount of minerals for optimum extraction.

We can assess mineral content by looking at the ‘total dissolved solids’ (TDS) in a water. This is measured in ppm (parts per million). A water with 150 ppm (same as mg/l), or something similar, is best for coffee. Also, look out for water with a little more magnesium than calcium – Mr Mg is great at flavour extraction and brings lovely fruity notes to your cup.


Visual graph describing the best type of water for coffee brewing



Is Hard or Soft Water Better for Coffee?

You’ve probably heard of water hardness. But is hard or soft water best for coffee?

Hardness describes the amount of dissolved minerals in a water. Calcium and magnesium are the main minerals we focus on when chatting water hardness.

Soft water is low in these two coffee-loving minerals, while hard water is overflowing with ‘em. Generally, we see 50 ppm as soft water and 180 ppm as hard water.

Is your water hard or soft? It depends on where you live:

  • Soft water: Scotland, Ireland and Wales
  • Hard water: South East of England and London


Pouring water into AeroPress sitting on a red mug



Why is Hard Water Bad for Coffee?

Some hardness is important, but we don’t want too much. Because hard water contains minerals (which extract flavour), it alters the rate at which all those substances in coffee enter into the solution.

What’s more, hard water is bad for your precious coffee equipment. It can cause limescale build-up in your tools and espresso machine, and a clogged-up machine is never going to give a good cup, is it?

So, what’s best? If you live in a hard water area, you might want to consider a softer alternative. You could use a water filter or try bottled water. Just please, please try to keep the plastic bottles to a minimum – we all know they’re awful for the environment.

Reading this from a soft water area? Well, aren’t you lucky… your water is pretty good for coffee as it is!




What are the different types of water?

Ever tried using distilled water for coffee? Disappointed by the result? Find out why in this handy water glossary. Trust us; it’s the mini dictionary you never knew you needed…


Making cold brew coffee with filtered water


Tap water is water that comes from your home tap. It looks clear but contains solubles and minerals from the soil. Water companies also add a teeny amount of chlorine for disinfection. This is safe, of course, but it can contribute to an off taste in your coffee.


This is water that has been boiled into vapour and then condensed back into a liquid. Distilled water for coffee isn’t a good shout because it contains no minerals, and you know minerals are super-duper important for flavour extraction…


Purified water is squeaky clean. It’s just a bit too clean. As well as all the bad bits we don’t want, purification gets rid of all the good bits we need for great coffee. Put simply; it’s too pure.

Reverse Osmosis (RO) is one water purification process you might hear about. There are no minerals in RO water, making it a bad choice for coffee brewing.


Use a water filter, and you’ll remove the major impurities from your H20 but leave the natural minerals where they are. Yippee! Your coffee beans are smiling.

Water filters like a Brita water filter won’t soften hard or very hard water fully, but they’ll take you on your way to a water win!


Brita water filter on a table with AeroPress and white bowl of coffee



What is the Best Type of Water for Coffee at home?

The SCA is the main coffee body. They’ve set out some coffee water guidelines:


Odour: none

Chlorine: none

Alkalinity: 40 ppm

Ph: 7.0

Calcium hardness: 4 grains or 68mg/l


This is a bit sciencey, we know, so here are some simple guidelines to help you get the best water at home:

      • Take a good look at your water. It should look and smell clean and taste lovely and fresh. If it doesn’t, don’t use it – for coffee or anything else!
      • Then, do a bit of research. Do you live in a hard or soft water area?
      • If you live in a soft water area, you’re good to use tap water as it is. A spot of filtering won’t hurt, though.
      • If you live in a moderate or hard water area, you have a little more work to do. Sorrreee… Brita water filters won’t solve the problem of hard water but are a good place to start. Bottled water is a solution, but a not-very-eco-friendly one.


Pouring hot water from kettle into cafetiere


Always take a look at the label if you are buying bottled; many contain no minerals or way too many for good coffee.  Remember, you’re after a water with TDS of 150 mg/l, a good amount of magnesium and adequate bicarbonates. This means a calcium hardness of 68mg/l and a total alkalinity of 40 mg/l. These are the absolute optimums – anything around these figures will be awesome!

If you want to know more about your water, try using a water testing kit. You can pick these up from pet shops. Yes, you read that right! It’s because fish owners need to test the water in their tanks.



What’s the other liquid that goes into your coffee? Milk!


Find the best milk for coffee below!


Guide to milk

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