Acidity/alkalinity, on a 0–14 scale where 7 is neutral. Below 7 is acidic; above 7 is alkaline.
Why it matters — Brewing water should sit around 6.5–7.5 pH. Acidic water (below 6.5) corrodes copper and brass boiler components over time. Highly alkaline water (above 8) mutes coffee flavour and reduces extraction.
Good to know
- Most municipal water in Australia sits within the acceptable range.
- Reverse-osmosis water often drops to slightly acidic — remineralisation cartridges restore both pH and mineral content.