You just cracked open a fresh bag of a 97 point scoring Panama Geisha that you splurged on for the holidays from that out of state roaster you’ve followed for years on instagram, whose single 12oz bag of this coffee was equal to your next phone bill. You make sure to follow every step of the brewing instructions by your favorite silver haired youtube connoisseur, to include making sure that the coffee hand ground and roasted only days ago. Sitting down to enjoy an experience that is surely to open lines of dialogue with long dead relatives, you taste the coffee and its.. fine. Its good, but its also.. just fine. What happened?
Answer: Water – And heres why.
General Hardness
Water alone cannot extract all of the things necessary to make a great cup of coffee. To do so, we rely on certain elements and compounds within the water to bind to flavor components and bring them with as they enter the cup. However, as we’ve commonly experienced brewing at home or in different cafes, too much of anything can produce a negative result. The same thing that clogs your shower head and makes your coffee pot run slow could be the same thing that is making your coffee taste bitter, dull or chalky. The culprit: Calcium and Magnesium.
Both of these elements are crucial during extraction, as they increase the binding potential to the electron-rich organic molecules in coffee that water by itself would not be able to. (To test this fact, try brewing with distilled or deionized water and notice the reduction in flavor). Unfortunately, as you increase the amount of Ca and Mg in water you run into the issue of leaving less room in the water to absorb coffee compounds, and increasing the perception of the flavor of the minerals. The more saturated or “hard” your brewing water is , the lower your perceived complexity becomes and fewer favorable compounds are able to be carried into your cup. Not to mention damaging your brewing equipment over time.
To determine the hardness of your water, we recommend using a general hardness test kit on your water at home like the one listed below. Water within a general hardness range of 50-150ppm is considered acceptable, and within 75-125 being ideal.
Drop Test kits are more accurate than TDS meters as the test the chemical composition of water, not just the conductivity.
Carbonate Hardness
Brewing coffee is more like baking, and less like cooking. Far less forgiving to variation and reliant on the chemical interactions that compounds have in concert with the kinetic energy provided by a high heat environment that changes flavor on single digit increments. Simply put, your coffee can do some really weird things in the presence of different compounds. Enter carbonate and bicarbonate. The mediators or “buffer” most commonly present in water that shakes hands with the weak acids and turns them into something they are not. It does this by stealing one of the protons of the weak acids and converting it to a weak base, effectively decreasing the perception acidity. (see Conjugate Acids & Bases)
Unfortunately, some acidity is necessary in providing a great cup of coffee. An excess of Carbonate and Bicarbonate can convert all of your weak acids into weak bases, and makes your cup of coffee taste bitter.
Balance is key. It is difficult or impossible to impact your carbonate hardness without also impacting your general harness. Using the same testing kit as recommended in the general hardness section, you can establish whether your water has too much, or too little or our buffering friend. An acceptable range for carbonate hardness is between 30-60ppm.
Contaminants
You’ve figured out your Carbonate Hardness and General Hardness, and your water is perfect. But you still feel like there is something off about the coffee in your cup.
In much of the world, the water from our taps doesn’t come straight from the ground. In order to provide safe and consumable drinking water, municipalities process water by treating it with chemicals like Chlorine or Chloramine. In households or buildings where water is naturally very hard, it is treated by using softener salts. These additions either introduce off flavors or completely strip our water of good compounds by replacing them with ones that don’t interact with coffee. Additional contaminant that could be impacting your water -
Metals (Rust or copper from old pipes)
Plastics (PEX piping in new homes or apartment complexes)
Sulfates (fertilizers entering groundwater)
Bacteria (old water filters, or dirty brewing containers)
Solutions
You’ve learned a lot about water, now its time to change it. There is no one-size-fits all fix to each and every water problem. But there are options available within reason that make brewing cafe quality coffee at home a possibility.
Filtration
This may be the first step for many. Ranging from simple pitcher filters to Reverser Osmosis.
A simple high-capacity gravity fed and multi-stage system that filters without discretion + reintroduces some valuable minerals to improve extraction. Great for home-use with well water or city water.
Bestmax Filtration + Filter Head
Heavier duty cycle and longer lifespan. Great for the prosumer, schools, churches or small cafe opertations. Simple install for the handy, but professional install is recommended.
The Big Kahuna. Great for coffee shop or high volume cafe, or those working with softened water. Filters everything from salts to contaminants and allows you to tune your water through needle valve reintroduction and remineralization (plus a built in TDS meter). Professional install required.
Addition
The opposite of filtration with an increased fun factor. Starts with a baseline of deionized or distilled water and manicuring it to the perfect amount of dissolved solids.
With options designed for home espresso makers and drip coffee brewers, Third Wave Water has provided us with some really cool options for the at-home connoisseur. Designed for use with deionized or distilled water which can be found in most grocery stores.
3-to-1 ratio
A method we developed ourselves at home, reliable and cheap although a little more laborious. Take 3 parts distilled water and mixed with 1 part tap water and adjust to taste. This will not remove any contaminants, but does reduce your overall water TDS. Great for hard well water.