What is TDS in water and why does it matter?
TDS stands for Total Dissolved Solids, a measure of the combined content of all inorganic and organic substances contained in a liquid. In coffee brewing, TDS indicates the mineral concentration of your water. An ideal range of 75–150 ppm ensures water can effectively extract flavor compounds without being too hard or too soft for a balanced cup.
TDS, or Total Dissolved Solids, is one of the most important metrics for understanding your brewing water. It represents the concentration of dissolved minerals—such as calcium, magnesium, and sodium—as well as other particles in your water. Because water is a solvent, its ability to extract flavor from coffee grounds is directly tied to what is already dissolved in it. If your water is already "full" of minerals, it will have less capacity to extract the delicate acids and sugars from your coffee.
If your TDS is too high, your water is considered "hard." Hard water is often rich in calcium and magnesium, which can bind to the compounds in coffee and lead to over-extraction. This often results in a cup that tastes bitter, chalky, or overly heavy. Furthermore, high TDS water is the primary cause of limescale buildup in espresso machines and kettles, which can damage your equipment over time and affect the consistency of your brew.
On the other hand, if your TDS is too low, your water is "soft" or "empty." While this might sound pure, water with very low TDS lacks the minerals necessary to facilitate proper extraction. Without these minerals, the water may aggressively extract only the most soluble compounds, leading to a cup that tastes thin, sour, or unpleasantly acidic. It lacks the body and sweetness that balanced water provides.
For the home brewer, the goal is to find the "sweet spot" where the water is mineralized enough to extract flavor but not so mineralized that it masks the coffee's character. The Specialty Coffee Association (SCA) recommends a target TDS range of 75 to 150 ppm. This range provides enough buffering capacity to balance the acidity of the coffee while allowing the unique flavor notes of the origin to come through clearly.
In practice, you can use a simple, inexpensive TDS meter to check your tap water. If your reading is outside the recommended range, you can use filtration or mineral additives to adjust it. By managing your water's TDS, you take control of the most significant variable in your brewing process, ensuring that your coffee tastes consistent and delicious every single time.
- · https://sca.coffee/research/coffee-standards