You can’t brew coffee without water. Next to the beans themselves, water is the most important ingredient in any espresso shot or cup of coffee. But it goes even further than that–different water types can affect the extraction of coffee as well as the taste. You might’ve wondered before why the coffee you brew at home just doesn’t measure up to the stuff you get at the cafe, even if you use the same roast. Your water could be the culprit.
In this guide, we’ll dive into just how water can influence the taste of coffee and analyze the best water types to use so you can make consistently great coffee every time.
How Water Impacts the Taste of Coffee
To understand how water impacts the taste of coffee, you need to first understand what’s typically found in water. Most tap water around the country has varying degrees of minerals added when it undergoes treatment. Calcium, magnesium, and potassium are the most common minerals in tap water. These minerals are not harmful at all. In fact, they are generally good, though their primary benefit in water is to make it taste better.
The ratio of minerals to water is what determines whether your water is considered “hard” or “soft.” Hard water contains a much higher mineral count than soft water, and many people prefer the taste of hard water when drinking it plain. These minerals in the water actually enhance the flavor of coffee during the brewing process, but a mineral content that’s too high or too low can all but ruin the taste. Additionally, hard water can cause mineral buildup over time which can affect the performance of your espresso machine.
What About Total Dissolved Solids (TDS)?
Many baristas concern themselves with the total dissolved solids or TDS in the water they use. TDS refers to the total concentration of dissolved substances in drinking water, including inorganic salts and organic matter. You can easily measure the TDS of your tap water with a TDS meter.
The widely recommended TDS of water for coffee is between 30-100 TDS, but this isn’t really a hard-and-fast rule. Some roasts shine with a low TDS while others prefer higher TDS. Furthermore, TDS doesn’t really take into account the combination of minerals and other compounds that affect the taste of water.
Some baristas take the ratio of hardness and alkalinity (or carbonate) into consideration when choosing water for coffee. Alkalinity is water's capacity to resist acidic changes, which is a fairly important quality when dealing with coffee. You need a certain degree of alkalinity balanced with the hardness level of your water to extract the best flavors from your coffee. A 2:1 ratio is often considered ideal.
Types of Water
There are many types of water out there and not all are created equal when it comes to brewing coffee.
Distilled water is made by boiling water until it vaporized and condensing that steam back into water. This method removes impurities and minerals from the water. Distilled water is potable and therefore can be used to make coffee, but take caution: because the minerals have been removed, distilled water is not as tasty as tap water and it has a tendency to leach minerals from whatever it comes in contact with, including your coffee brewing equipment.
We don’t recommend using distilled water to brew coffee or espresso.
Reverse Osmosis (RO) Water
Fresh Water Systems says it best: “Reverse osmosis removes contaminants from unfiltered water, or feed water, when pressure forces it through a semipermeable membrane.” This process results in pure drinking water free from contaminants, molecules, and minerals. Most bottled water companies use reverse osmosis to treat their water. Reverse osmosis water is great to drink, but doesn’t always produce the tastiest coffee because it lacks minerals.
We don’t recommend using RO water to brew coffee or espresso.
You can invest in an RO water system that allows you to bypass tap water. Bypassing tap water means that you primarily use RO water and add a small percentage of tap water to add minerals for flavor. This is a great way to filter out contaminants from your drinking water while keeping the ability to brew a great cup of coffee.
Purified water undergoes filtration to make it safe to drink. Most municipal water suppliers purify drinking water before it’s distributed, but you can buy water filter pitchers to take this a step further. Filtering tap water removes excess calcium that causes build-up as well as compounds that don’t taste good.
Alkaline water has a higher pH level than regular water, about 8-9 pH compared to a neutral 7 pH. Alkaline water contains magnesium and calcium, but it also contains alkaline minerals and negative oxidation-reduction potential (ORP) that acts as an antioxidant.
Now you know the types of filtered water out there, let’s look at the best water for your coffee and espresso.
The Best Water for Brewing Coffee
Purified water is one of the best types of water to drink and use for brewing coffee. By filtering out contaminants and excess minerals, you’ll be using tasty water that doesn’t cause much build-up in your equipment. It’s also incredibly convenient, as most water filter pitchers are reasonably priced and can be easily stored in your fridge.
Alkaline water is also great for brewing coffee. The alkalinity boosts flavor and neutralizes bitterness to help brew a delicious cup. Alkaline water pitchers are also easy to find and keep in your fridge.
Avoid using distilled water or RO water as these types can leach minerals from your brewing equipment and eventually cause damage. Additionally, since no minerals are present in these water types, meaning your coffee will not be as tasty.
While the type of water you use can influence the taste of your coffee, so can coffee to water ratio.
The Best Water for Espresso
Soft, filtered tap water and filtered alkaline water are also the best types of water to use in espresso machines. Unfiltered hard water causes build-up within the pipes of espresso machines which affects the taste of your coffee and can cause your machine to break down.
Though it might seem like distilled or reverse osmosis water would be great considering the purity of these water types, they can actually cause just as much damage to your machine as hard water. Water is an incredibly powerful solvent, so it stands to reason that ultra-pure water can even leach out minerals from your pipes and corrode them.
At-home espresso machines typically have water reservoirs which can easily be filled with filtered water from the tap, but commercial espresso machines can be connected directly to your water line. If you happen to have one of those espresso machines at home, make sure an alkaline filter is installed to reduce the minerals in your water to keep your machine at peak performance.
Learn more: How to Choose a Home Espresso Machine
Descaling Coffee and Espresso Machines
Whether you use unfiltered tap water or a RO bypass water system, descaling your coffee equipment is essential. Regularly backflushing and descaling your espresso machine prolongs the life of your equipment and keeps your espresso tasty. If you want to brew a great cup of coffee every time, don’t skip this step.
Learn more: How to Clean Your Espresso Machine
Best Water Filters For a Great Cup of Coffee
Here are a few of our recommendations for water filters that will help you brew a perfect cup of coffee or shot of espresso every time.
Brita is probably one of the most popular water filter systems out there. You can find this filter nearly anywhere. Brita filters out chlorine, copper, zinc, mercury, and other harmful compounds, yielding delicious drinking water perfect for brewing coffee.
If you want to go the alkaline water route, this water filter from Ehm is a highly recommended choice. The Ehm alkaline water filter pitcher removes free radicals and toxins, removes acidic compounds, and delivers delicious water that helps brew a delicious cup of coffee.
Commercial-Grade Water Filtration Systems
Many coffee shops invest in a commercial-grade water filtration system to get the best water for coffee. Most of these water filtration systems use reverse osmosis to purify the water, so cafes usually bypass a bit of tap water for minerals and flavor.
If you’re interested in reverse osmosis water filtration, this system from Express Water might suit your needs. This under-the-sink filtration system purifies tap water through reverse osmosis and adds minerals back in for flavor–no need to add your own.
It’s All Relative
Choosing the ideal water type for brewing coffee is largely a matter of taste–no pun intended. What matters is finding the water type that helps you consistently brew your favorite cup. Whether you use alkaline water or filter tap water, we’ve got the perfect roast for you.
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