Lesson 3 - Brewing Water Sources and Treatment SAQ

*Write short answers to the following questions:

a) What is water hardness? Describe what total water hardness is, and what it consists of.

b) What is the definition of total alkalinity; how is it expressed?

c) What is residual alkalinity? Provide two methods that calculate the residual alkalinity in water.

d) Traditionally, what type of water hardness would you use to brew a pilsner and a pale ale?

e) What is surface water and ground water?

Response:

a) Water hardness is determined by the level of naturally occurring calcium Ca and magnesium Mg compounds in your water. High levels of these compounds make the water ‘hard’, whilst low levels make the water ‘soft’. Total hardness mainly consists of the salts of Ca and Mg cations, with bicarbonate, carbonate, sulphate, chloride and nitrate ions.

b) Total alkalinity is defined as the amount of strong acid required to convert the carbonate and bicarbonate in the sample to CO₂ at a pH of 4.4. It is expressed as mg/L of calcium carbonate (CaCO₃).

c) Residual alkalinity is any alkalinity remaining after it has reacted with phosphates in the mash water (mainly from malt). Any residual alkalinity increases the mash pH. It can be calculated using the following two calculations:

Or,

it can be calculated using the alkalinity provided by the bicarbonate ions (HCO₃^1-) using the following equation:

d) We should use soft water for a pilsner. A pale ale would use hard water.

e) Surface water is any body of water that is above the ground, such as ponds, rivers, lakes, streams. Ground water is surface water that has seeped into the ground, through rock and soil layers and into the aquifers below.