Water for coffee
Water accounts for approx. 98% of your morning cup of coffee (92% for espresso). You wouldn’t be able to make a coffee without it, so it makes sense we understand what’s in it, how it tastes, and whether it’s helping or hindering your coffee brewing.
Researching water chemistry can open up a serious rabbit hole. In this article, we’re going to try and keep it as simple as possible. We encourage you to refer to our references for more information (see at the end of the article).
From the sky to your cup
Australia is one of the driest countries in the world. This means we can’t rely on rainfall for our water needs.
Water Corporation offers a feature on their website where you can type in your address and see where your home’s water is sourced from. For example, from our coffee roastery here in Bibra Lake, Perth, our tap water is a a combination of water sources; desalination, ground, dams and replenishment.
Although H2O appears clear and devoid of anything but, well, water! There are extra properties in the liquid to ensure your glass is clean and safe. This will depend on where your water is sourced from and what treatment process the H2O has gone through. For example, water sourced from a dam is going to be treated differently compared to ground water.
After treatment, water is chloraminated (chlorine and ammonia). This stays in solution longer to deliver microbiologically safe potable water for your home use. Impurities are filtered out, the water is disinfected, and various other minerals (such as fluoride) are added.
For those who are living in Perth (us included), there is some bad news…
Brace yourself… Perth water contains 0.5 – 1.5ppm (parts per million) of chlorine. Compared to Melbourne, which has around 0.3ppm – this is quite a big jump. Although chlorine in this micro quantity is perfectly fine for human consumption, this addition gives tap water a distinct “chlorine-y” taste. Alongside this, the infamous chlorine taste is more prominent in warmer weather. Considering how hot the weather can get here in WA, it’s no surprise Perth is renowned for having the worst water in Australia.
Best water for coffee
Here is where the fun begins. Many have experimented with making their own water in search of the very best water recipe. See here for Barista Hustle’s DIY water recipe.
Ideally, you want water with little chlorine. If you’ve accidentally swallowed water whilst attempting butterfly at your local swimming pool… you’ll understand why. Simply put – it’s unpleasant and will diminish coffee flavour (by reacting with the coffee and causing a bitter taste) if not filtered before making your coffee.
Fluoride can also alter the flavour of the water, increasing the acidity levels.
High levels of iron or copper can create a metallic tang.
Calcium and magnesium carbonates are the cause of scale build-up in machinery.
However, paradoxically, you need a specific balance of these mineral ions as they help with extracting the coffee flavours. If you have no mineral ions, you’ll have very little extraction.
Soft and hard water
Hardness comes from contact with minerals rich in calcium, magnesium, and anything really the water passes through. As soon as the water hits the ground, the rain begins absorbing minerals. Most of Australia is built on limestone bases, this allows for better water flow, yet also dramatically increases the calcium naturally present in the limestone.
Hard water is also very problematic for espresso machines as it causes limescale. Limescale is a concoction of calcium and magnesium found in hard water and particularly where water is evaporated.
Tap water poured into a kettle is the ideal environment for scale build up… so don’t say we didn’t warn you next time you inspect your kettle’s vessel.
Ideally, we want the perfect balance of hard and soft water. Too hard (tap water in Perth), will result in unpleasant flavours in our coffee. Too soft (rainwater) and our cuppa will taste muted as it’s unable to effectively extract the flavour of the coffee grounds. We’re looking for an in-between that’s just right (as Goldilocks would say).
**Please note: a level of hardness is unavoidable for water as it’s impossible to remove all elements. This means the interior of your coffee machine will need to be descaled to reduce calcium build up.
Another component to think about when it comes to water is the alkalinity, which refers to the buffer capacity of a water body to neutralize acidity and maintain a stable pH level.
Ultimately, we want water to have a pH level of around 7 (pH scale is 0-14. Below 7 is termed acidic and above 7 is alkaline). If lower, the water can eat away the inside of the coffee machine and mute coffee flavours. Higher, results in alkaline. And, if there’s too much alkaline, it will result in an acidic and a chalky tasting cup of coffee. Generally, high alkalinity goes with higher hardness. Desalinated water has no hardness i.e. calcium and magnesium so the water authority raise the pH to take the aggressive edge out of the water.
Check our James Hoffman’s video on water here.
Finding the middle-ground is essential and will play a big part in doing your specialty Karvan coffee beans justice.
Water we use for our coffee
Although it can be a fun process to create your own water truly, it’s quite a timely method… particularly if you own a café. The easiest, most effective and reliable solution is Reverse Osmosis with magnesium remineralisation post treatment.
We use a Reverse Osmosis system at our Perth coffee roastery. RO is used for all of our coffees and teas. We use it for our water in our kettle, for cupping sessions, making coffee and even drinking water. With all of the cafes we supply to, they put their water through RO.
For home coffee lovers, we highly recommend treating yourself to Reverse Osmosis with post treatment and/or having good quality filtration at home. If you’ve ever read the taste notes present on your bag of coffee and have been confused at the taste notes… this could be why. Water makes a dramatic difference to your espresso!
A big thank you to Glyn from BWT for making sure the water at our roastery is the best in the buiz!
Want to learn more?
Check out these resources for more info on water for coffee.