Does the type of water matter?

Because coffee is overwhelmingly water, the liquid you use is not just a carrier for flavor—it is the primary solvent responsible for extracting the oils, acids, and sugars from your coffee grounds. If your water is 'hard' (high in mineral content like calcium and magnesium), it can lead to excessive extraction or scale buildup in your machine. Conversely, water that is too 'soft' or distilled lacks the necessary minerals to pull out the coffee's full flavor profile, often resulting in a thin, flat, or unpleasantly sharp cup.

The Specialty Coffee Association (SCA) suggests that ideal brewing water should have a total mineral content between 75 and 250 parts per million (ppm). While these numbers provide a helpful target, the specific composition of those minerals—particularly the balance of magnesium and calcium—is what truly dictates how your coffee tastes. Magnesium, for instance, is excellent at pulling out fruity and floral notes, while calcium contributes to a heavier, creamier body.

Beyond mineral content, the presence of chlorine or other impurities from municipal treatment plants can introduce off-flavors that mask the delicate nuances of your beans. If you wouldn't drink a glass of your tap water on its own, you shouldn't use it to brew your coffee. Many home baristas find that a simple charcoal-based filter pitcher is enough to remove chlorine and improve the taste, while others in areas with extremely hard water may opt for bottled water or specialized remineralization systems.

In practice, the best approach is to start with clean, odor-free water. If you are curious about your specific water profile, you can use an inexpensive TDS meter to get a snapshot of your water's mineral content. However, don't get too caught up in the numbers; the most important rule is to use water that tastes good to you. If your coffee tastes dull or sour, experimenting with a different water source—like a high-quality filtered tap or a balanced bottled water—is often the easiest way to elevate your home brewing game.