How does water pH affect coffee?

The common obsession with water pH is a classic case of mistaking a symptom for the cause. While the Specialty Coffee Association (SCA) suggests a pH range of 6.5 to 7.5, pH is merely a snapshot of the hydrogen ion concentration at a single moment. It tells you nothing about how the water will behave once it hits the coffee grounds. The real mechanism at play is alkalinity, or buffering capacity, which is primarily governed by bicarbonate levels. When hot water meets ground coffee, it extracts a complex array of organic acids. If the water has low alkalinity, it lacks the 'buffer' to neutralize these acids, leading to a sharp, sour, and often thin-bodied cup—regardless of the starting pH. Conversely, excessive alkalinity can mute the vibrant, fruit-forward acidity that producers work so hard to cultivate, resulting in a flat, chalky, or dull brew. For the producer, this is a critical distinction: a farmer may deliver a high-scoring, bright, and complex lot, only for it to be rendered one-dimensional by a brewer using water that lacks the mineral stability to balance those inherent acids. Misunderstanding this leads many to chase a 'neutral' pH of 7.0, when in reality, a slightly alkaline water with appropriate bicarbonate levels is often the secret to a balanced, sweet extraction. Focus on total alkalinity and mineral content rather than the pH meter to truly honor the producer's work.