Water and coffee: It’s just water, right?


You’ve meticulously selected or roasted your coffee beans, ground them just right and brewed your coffee to perfection. Or have you? How much attention did you pay to the water you used? Your delicious brewed coffee is 98% water, so it might just pay to spend a little time understanding the effect water can have on your brew.

Water chemistry is complex. What we are particularly interested in is mineral levels of the water and how the minerals interact with one another. Even more importantly, how they interact with your coffee. Too many or too little of certain mineral content will detrimentally affect your extraction and could result in either a bland or over-extracted, harsh and bitter brew.

Hard and Soft Water

“Hard” and “soft” are terms used to describe water with high and low mineral content, respectively. The source of the water impacts the water “hardness”. Underground water is harder than surface water (eg. from rivers and streams). This is because underground water has far greater exposure to minerals over time. Magnesium, calcium and carbonate are important minerals to monitor.

In addition to minerals, water may contain pollutants, water treatments, or even the chemicals used to disinfect water mains pipes. The material used to construct the water pipes can also affect the chemical composition of the water, leaving chlorine and hypochlorite traces that will taint your coffee experience!

Water pH

The pH of water is affected by minerals and contaminate content. You guessed it! This is also important for your brew quality.

Ideal Water

The Specialty Coffee Association (SCA) has described the standards for high quality water. You can see these on the SCA website. In general, most water around the world is too high in both carbonate hardness and total hardness and need some treatment to elicit a perfect brew.

These basic filtration methods can improve your water:

  • Micron filters remove particles and bacteria

  • Carbon filters remove chemicals, pesticides, bad tastes and odours

  • Magnesium cartridges add magnesium (essential for extraction of desirable flavours)

One Final Piece of the Puzzle

Often overlooked, yet vastly important is carbon dioxide (CO2) in the beans themselves. Not technically part of the water problem, CO2 forms when the coffee is roasted and becomes trapped inside the bean. Coffee beans release the majority of CO2 in the first few days following roasting. This is a whole other blog post in itself – but simply put, the CO2 reacts with hot water to form carbonic acid, which alters the pH of the water and results in an acidic, sour and tangy brew.

What to do?!

In a commercial setup, water is tested, and the mineral content is analysed. Appropriate filtration or re-mineralising is undertaken to restore ideal mineral content. While this might be too much for the office, there are a few easy solutions for improving the water for your home or office brew.

Water Solutions

  • Water filtration jugs, such as those with Brita filters, remove chlorine and reduces carbonate hardness (acts as a water softener), and also help to reduce copper and lead particles.

  • Bottled water is generally well balanced and sits within acceptable limits of hardness and other chemical content

  • Third Wave Water has developed a sachet for optimal remineralisation of distilled water (which is completely devoid of any minerals)

  • If you are quite enthusiastic, you can make your own balanced water by finding a recipe using minerals available from the supermarket!

Coffee Bean Tips (to reduce CO2 related issues)

Filter Roasted Beans

  • Allow 3-4 days post roast to allow the bulk of CO2 to escape

  • If you need to use fresh beans, increase your bloom time to 45sec, blooming rapidly releases the trapped CO2

  • Tip out any run through from the bloom

Espresso roasted coffee

  • Allow 10-14 days post roast to allow CO2 to be released

  • Most espresso machines do not bloom reliably, so it is not recommended to use this method to force a rapid release of trapped CO2. You should allow the beans to mature naturally.

Getting water quality and CO2 content under control are very simple ways to take your brew to the next level – give it a shot!

Cold-Drip Advanced Brewing and Explanations


If you have not yet done so; please read the article "Brewing Instructions", this blog is an extension of The DripLab Cold-Drip setup and the processes involved.

Filter papers
The two filters are very simple. The rectangle is a pure cotton filter, it functions to hold the coffee grinds back. The round filter is thin filter paper and functions to encourage the water to disperse and keep the coffee grinds in place, without this the water would create a crevice.

Creating the dome?
This assists the water to disperse more evenly.

Filter roasted beans, espresso roast or a mix of both?
This will depend on how you wish to use the brew. Whether you love the bold body and strength of an espresso, a smooth latte or a bright cup of black filter coffee the guide below will help you chose a profile that suits.

Have a good chat to your roaster or barista, most coffees will have some tasting notes with them, this will help guide you to to brew something you favour, strawberry and tropical fruits will be great as a iced long black, while caramel, malt and cocoa will shine as an iced latte.

Filter Roasted Coffee
Pros: complex flavours, bright, fruity & aromatic, great used for iced long blacks.
Cons: light body, requires more concentrate to make beverages = extra caffeine, does not mix great with milk, does not work well in espresso martinis!

Espresso Roasted Coffee
Pros: caramels & chocolates, big body, great with milk , great in espresso Martinis!
Cons: less complexity, less fruity, less aromatic, not great as iced long blacks

Mixed (1 part filter 2 parts espresso)
Pros: bright, fruity & aromatic with chocolates and caramels, good body, great as iced long blacks and also works well with milk. Uses less concentrate to make beverages, good body, also suitable for espresso Martinis!

Post Roast Development
Have you ever noticed those little one way valves on your coffee bags? These allow gas to escape without letting oxygen enter. Oxygen causes your coffee to oxidise (you don’t want this).

When a coffee bean is roasted, carbon dioxide (CO2) is created and trapped within the bean. This gas slowly escapes from the bean over time. Ideally you should allow 12+ days for this process to occur after the coffee has been roasted. Using the beans prematurely can cause the CO2 gas to block water from dissolving the solids.

Blooming is a method used in filter brewing. The coffee grinds are saturated with water and left for 20-40sec. Blooming causes the coffee to swell and facilitates the rapid release of CO2. When the remaining hot water is poured over the coffee there is little resistance from the CO2. This allows the water to extract those tasty flavours.

You can use this same method if you are working with very fresh coffee, however, because hot water is not used with cold-drip, bloom time should be extended to 5-10min.

Water quality is very very important and commonly overlooked. I’m sure we have all tasted bad tap water at some point, tap water can often have either too much or too little of certain minerals required to extract and carry those flavours into your brew. Ensure you are use quality filtered water, it will make a huge difference to your brew.

I often see ice recommended in the water dropper. I do not recommended this. When we brew coffee we chase sugars which help balance flavour. This literally is the difference between terrible, good and amazing brews. The easiest way to explain, take two glasses of water, one with ice and one at room temperature. Try to dissolve ½ a teaspoon sugar in each. It is much more difficult to dissolve in iced water. The room temperature water takes time but the sugar will eventually dissolve.

Oxygen and nitrogen can dissolve in water, the amount dissolved depends on the waters temperature, among other conditions like atmospheric pressure. When you fill a glass with water from your kitchen sink and allow it to warm up to room temperature, oxygen and nitrogen slowly comes out of the water. These tiny bubbles form and collect on microscopic imperfections on the glass.

Why am I telling you this?

These little bubbles can stall your water drops. Allow your water to reach room temperate and stabilise before you fill the water vessel, this inhibits these bubbles forming. If you have invested in a water filtration jug, leave it on the bench. It will always be ready and you brews will be sweeter and balanced.

Always keep your cold-drip covered and in the fridge. Your brew will develop over several days and improve in body, give it a day or 2 and compare against a fresh brew. I recommend to use within a couple of weeks, however, it can last several months with appropriate storage.

Happy Brewing :)