Everything About Water For Coffee Brewing
98% of coffee is water! The type of water you brew coffee with will significantly affect the taste of your coffee, hence it's super important to get this right for the most delicious coffee every day!
Perfect water for perfect coffee
Types of Water
There are a couple of types of water that you can easily find anywhere in Malaysia.
Distilled water is steam from boiling water that's been cooled and returned to its liquid state. This method get rids of impurities & removes more than 99.9% of the minerals dissolved in water.
Reverse Osmosis, commonly referred to as RO, is a process where you demineralize or deionize water by pushing it under pressure through a semi-permeable Reverse Osmosis Membrane. You can find both types of water in white bottle cap in supermarket.
Distilled & reverse osmosis water have zero minerals content, ie 0 ppm. But for coffee brewing, you need a certain amount of minerals to fully extract the flavours & sweetness from ground coffee. Hence, coffee often tastes flat and bland if you brew with RO/distilled water. We don't recommend at all ⛔️
Mineral water is alkaline & not good for coffee
Mineral/spring water have higher ppm than filter water and is very often a little alkaline because of the presence of calcium content. (see PH at 7.6)
Calcium neutralises acidity in coffee. This makes coffee taste kinda heavy, muted acidity and easily over-extract your coffee with sharp bitterness on the aftertaste. It just makes any interesting coffee tastes boring 😣
Also, it builds up limescale in your kettle very quickly. So... not recommended 😕
That said, alkaline water is not good for coffee brewing too. It kills off any acidity in coffee and makes coffee taste dull 😑
Spring water for coffee? Maybe just for camping
Thankfully, our tap water is pretty soft with less than 100 ppm, depending on location. Just install a simple water filter and you are good to go! Yes, the best water for coffee is the one you have at home 🤗
One thing to note is there's still some calcium content in filter water. It will be best to have a water filter that is specially made for coffee to filter & minimise calcium content.
This is especially important if you brew with an espresso machine. Limescale easily buildup in the boiler & it will mute the acidity of coffee if you are brewing single origin coffees. Timely descaling your boiler is key to making delicious espresso! 😋
Lastly, if you are staying in an old building with old rusty water pipes. You may notice some metal taste even with filter water. For that, you might wanna consider ‘DIY water’ for coffee!
DIY Water for Coffee
If you realised that your tap water tastes kinda weird for coffee (eg. metallic etc) and you don’t want to spend it on a water filter. You can try out DIY water for coffee!
Three things that you need to get, baking soda sodium bicarbonate (Not baking powder), Epsom salt magnesium sulfate and distilled water. They can be found in supermarkets and pretty cheap too 🤗
Yes, distilled water is bad for coffee. But we are adding minerals to water that will increase its PPM & makes coffee taste amazing!
Easily found in supermarkets
Add 8.6g of baking soda and 25g of Epsom salt into 500ml distilled water. Shake until all dissolve. This is your mineral concentrate. (Credits to @baristahustle)
We like to use the 9.5l distilled water container, so you don’t have to repeat the same too quick too often (especially if you drink 4-5 cups a day 😁)
Then pour 32ml of mineral concentrate into the 9.5l distilled water (about 3ml per litre) And your DIY water is ready to brew! 🙌🏻
The more concentrate you put in distilled water, the harder the water (higher mineral content and ppm), the easier for you to extract coffee!
The perfect water for coffee!
Let’s say if you only brew with light roast coffee, you may want to use a little more concentrate (3.5ml per litre).
For us, we brew any coffees that come to our hand and they come to all kinds of roast levels. We don’t want to have too many minerals in water that easily over-extract darker roast coffees, we find the best at 3ml per litre 😊
Lastly, if you want to know how each mineral affects the coffee taste, try putting individual mineral into distilled water and brewing them.
What about brewing temperature?
About Brewing Temperature for Different Coffee
As you may have known, darker roast coffees are more soluble & much easier to extract than lighter roast coffee. The darker the roast, the more soluble the bean is 😲
Hence different roast level of coffee requires different brewing temperature to achieve the optimal extraction 😉 Getting the water temperature wrong will often result in to unbalance cup with overly bitter or sour taste.
Lighter roast coffee tastes better (in terms of extraction, body and sweetness) at higher brewing temperature, whereas darker roast tastes better at a lower brewing temperature.
Here’s our recommended brewing temperature,
Light roast coffee, try 95-98ºC
Medium roast, try 93-95ºC
Medium dark roast, try 90-93ºc
Dark roast, try 85-90ºC
As light roast coffee is not as soluble, it requires a greater amount of energy (heat) to extract all the flavours in light roast coffee. Hence a lower brewing temperature for light roast coffee often results in unpleasant sourness and hollowness from under-extraction, even brewing with a finer grind size 😧
The opposite for dark roast coffee, high brewing temperature easily result in over-extraction that super sharp bitterness and harsh aftertaste. With a low brewing temperature, you’ll get a smooth bittersweet cuppa with an everlasting sweet aftertaste.
We highly recommend making small adjustments of 1ºc within the recommended brewing temperature of each roast level.
Let’s say you are brewing light roast coffee with 95ºc and the coffee tastes a little acidic to your liking. You can try to brew with 96ºc on the next brew & this will makes the coffee taste lower in acidity 🤗
If the coffee tastes bitter, just drop 1ºc to 94-93ºc and your coffee will taste sweeter!
We also recommend to adjust the grind size first before changing brewing temperature. Changing grind size makes a bigger adjustments in extraction rate than changing water temperature that only make minor difference.
Lovely thin flow with gooseneck kettle
Top tips to brew coffee without thermometer 🤩
If you don’t have a thermometer or a temperature control water kettle at home (like us!), these tips are for you 🥰
As mentioned earlier, dark roast coffee is more soluble than light roast coffee. Hence we need to use a lower brewing temperature for dark roast & a higher brewing temperature for lighter roast coffee 😉
For brewing light and medium roast coffee, we recommend using boiling water to brew with! Yes, that’s right, BOILING WATER for light & medium roast coffee! 😮
Always use piping hot boiling water for light & medium roast coffee
Any brewing equipment will absorb a significant amount of heat, even it’s very well preheated. Your gooseneck kettle, French Press beaker, dripper & all will bring down the water temperature by at least 3-5ºc!
This can significantly reduce the extraction rate for brewing light & medium roast coffee. If your light roast coffee tastes watery & sour on the aftertaste, it’s most probably the water isn’t hot enough! 🥴
This is even more important if you are doing cupping coffee tasting. The room temperature cold cup will absorb lots of heat and under extract light roast coffee if the water temperature isn’t at boiling temperature. 😯
If you are trying to brew with boiling water for the first time, you can try with a 1-2 step coarser grind and pour vigorously to create higher turbulence.
Also, make sure you let all the coffee drain before pouring again on a pour-over method to keep extraction high for the sweetest cup.
85ºc the perfect temperature for dark roast coffee
On the other hand for dark or medium-dark roast coffee, you can add a dash of room temperature water into your water kettle to bring down the temperature! 🤗
Dark roast coffee is best to avoid brewing with 90c above high temperature. Even brewing dark roast with super coarse grind size, it’s very easy to over-extract with high temp and makes coffee taste sharp bitterness 🤮
A little lower brewing temp 80-85c is totally fine for dark roast, this makes the bitterness smoother & better sweetness! We would rather brew with lower temp to avoid the sharp bitterness that ruins your palate 🤢
Try it out & have fun brewing ☕️
