What quality of water is essential for making good espresso?

Good overall quality of water is essential for making excellent espresso because it directly impacts the extraction process and the final flavor profile of the coffee. Water interacts with the coffee grounds, and its quality influences not only the extraction of soluble compounds like oils and sugars but also the acidity and bitterness of the espresso.

Water that is free from impurities and has a balanced mineral content helps to achieve optimal extraction, resulting in a rich and complex flavor. If the water has unpleasant tastes or odors, these can also affect the espresso negatively, masking the coffee's natural flavors. Therefore, ensuring that the water is of good overall quality—clean, balanced in minerals, and free from contaminants—is critical for achieving the best results in espresso preparation.

While high mineral content is important to a degree to enhance flavor, extremes can lead to issues like scaling in machines. Low acidity levels alone do not ensure a good cup of espresso, as some acidity enhances flavor complexity. Soft water only can lead to under-extraction, as it may lack essential minerals that contribute to the flavor. Thus, the emphasis on good overall quality encompasses these factors effectively.