Lesson 2 - Brewing Water Sources and Treatment
This lesson introduces water as an ingredient for brewing. It explores the water cycle, sources of water and potability standards. It also examines some characteristics of water (hardness and alkalinity) and their effects on the brewhouse. Finally, the lesson investigates the methods of water analysis.
Precipitation
Precipitation starts as pure water. However, as it falls to the earth, it picks up carbon dioxide CO2, which acidifies it slightly to a pH of between 5 and 6.
In some areas of the world, where the pollution is heavy, the rain picks up sulphate (SO42-), nitrate (NO3-) and other inorganic compounds, as well as sulphurous and nitrogenous oxides. This can lead to acid rain with a pH as low as 2.6. However, rainwater is generally low in mineral content and very low in alkalinity.
Alkalinity measures the dissolved alkaline substances in water (higher than pH 7.0). It buffers (stabilises) water at a higher pH by neutralising acids. There are three primary types:
- Bicarbonate
- Carbonate
- Hydroxide
This means that rainwater from a non-polluted area could be a close fit to the required water quality. However, this is complicated by the impracticalities of collecting enough rainwater to meet a brewery’s full water requirements.