Water Basics
Water not only makes up the majority of a cup of brewed coffee, the composition of your water can have a large impact on how a coffee extracts while brewing. We can break water into a few main components:
H20: The Building Block for Water
Because of the unique shape of the molecule, water is attracted to other polar molecules and ions. Water, in its pure form, has a hard time brewing coffee, & will yield an under-extracted, thin cup.
Foreign + Organic Matter (target of 0ppm)
Large contaminants that are suspended in water. These are undesirable and cause off flavors in your coffee.
Municipal Water Treatment Chemicals (target of 0ppm)
While these chemicals are important to ensure safe drinking water, they can have unpleasant smells, even at super low concentrations.
General Hardness (target of 50ppm – 175ppm)
Composed of Calcium and Magnesium, this has a direct effect on water’s ability to extract. More hardness means better quality extractions, but can lead to scale build-up inside a machine. Over 175ppm of hardness can lead to overly-heavy flavors in your cup.
Carbonate Hardness (target of 40ppm – 75ppm)
Bicarbonate levels in water act as an acid-buffer, and will impact the perceived acidity in coffee. Too little will create thin, sharp acid flavors. Too much will yield a flat, dull, chalky cup.
Water Filters
The amount of filtration needed to adjust your water is largely dependent on the quality and composition of your local water source. A simple test kit from your local hardware store can help determine what filter is best.
Carbon Filters
The cheapest, and easiest filter to obtain, a carbon filter, will remove foreign matter, organic matter, and will reduce flavors from water treatment chemicals. This filter works great if your Calcium, Magnesium, and Bicarbonate levels are already at a pretty good level.
Reverse Osmosis + Mineral Addition/Bypass Addition
A little more complicated and the most expensive, a reverse osmosis filter system will really let you dial in your water. A Reverse Osmosis membrane will strip water down to almost no mineral content. A mineral addition system or filtered-bypass addition system will let you blend in small amounts of minerals back in to hit the target levels. Please note, plain RO water without a mineral addition/bypass addition will not have enough mineral levels to produce good coffee. Click here for our recommended one.
Dual-Ion Resin Filters
Resin filters can be used to specifically reduce levels of hardness and alkalinity in water. Often, they are paired with a carbon filter to deliver coffee ready water. Maxwell Colonna -Dashwood and Christopher Hendon, authors of the book “Water for Coffee” (the main source for this information), have recently launched a Dual-Ion Resin filtration system created specifically for brewing coffee at home. If you are looking for a coffee specific system, this one works well at a more budget friendly price point. Click here for our recommended one.
Take Away Tips
- Test your water to determine its composition.
- When in doubt, a basic carbon filter will go a long way.
- Descale your equipment if you notice white build-up. If you see excess build-up, consider a filter system that reduces scale.
- Try building your own water recipes to taste the difference before investing in expensive equipment.
Build your Own Water
Starting with distilled water, you can “build your own water” by adding minerals. Different levels of hardness and alkalinity will change the balance of your brewed cup. Companies like Third Wave Water sell pre-mixed packets to add to distilled water. If you want to get more hands on, custom water recipes can be made using epsom salt and baking soda. Recipes can be found on blogs online.
This article was originally written by Ben Turiano and published as part of our Coffee Tips & Myths e-mail series, focused on how brewing can impact what we taste. Ben is a certified barista trainer, a skill he has used to train our own barista staff, as well as consult for a wide range of wholesale clients. As Joe Bean's green buyer and head roaster, he has spent the last 10+ years building strong farming relationships worldwide, advocating for direct trade and mindful sourcing.