Brewing Water
Water Quality Parameters
Water quality parameters include physical, chemical, and microbial properties. Physical properties include suspended solids such as soil particles. Chemical properties are typically given the most focus when dealing with brewing water. From the brewer’s standpoint, the most critical chemical water quality parameters are pH, alkalinity, and water hardness. Microbial properties of interest include the presence of water-borne organisms. Laboratories will report values in different units depending on their protocol. Thus, it is often necessary to convert from one unit of measurement to another. Parts per million (ppm), milligrams per liter (mg/L), and milligrams per kilogram (mg/kg) are numerically equivalent and interchangeable.
Total Suspended Solids
Total suspended solids (TSS) are particles that are larger than 2 microns found in the water column. Anything smaller than 2 microns (average filter size) is considered a total dissolved solid (TDS). Most suspended solids are made up of inorganic materials, though bacteria and algae can also contribute to the total solids concentration.
Total Dissolved Solids
Brewing water from municipal water sources may contain total dissolved solids (TDS) such as minerals, salts, and organic matter. Total dissolved solids are a product of the aquifer media that the groundwater passes through before it enters a water well. Common cations that contribute to TDS are calcium, magnesium, potassium, and sodium. Common anions include bicarbonate, carbonate, chloride, nitrate, sulfates, and silicates.
Electrical Conductivity
Electrical conductivity (EC, also known as conductivity or soluble salts) is a term used to measure the total concentration of salts in irrigation water. A salt is a combination of positively charged elements (cations) and negatively charged elements (anions). The most common cations of interest in water are calcium (Ca2⁺), magnesium (Mg2⁺) and sodium (Na⁺); the most common anions are bicarbonate (HCO3¯), chloride (Cl¯) and sulfate (SO42¯).
Electrical Conductivity Meters
An EC meter measures the concentration all soluble salts dissolved in a solution but does not determine which salts are present at specific concentrations. Because of the impact of temperature, most commercial EC meters automatically compensate their output to account for temperature differences between samples.
pH
Water pH is a measure of the relative concentration of hydrogen ions (H⁺) to hydroxide ions (OH¯). The greater the number of H⁺ ions in relation to OH¯ the more acidic the solution becomes. The greater the ratio of OH¯ ions to H⁺, the more basic the solution becomes.
pH Meters
Electrode-type pH meters, which are the most accurate for measuring pH, are also the most expensive and require the most maintenance. Placing the pH probe directly into the solution until the reading stabilizes gives a quick reading.
Alkalinity
The alkalinity is arguably the most important parameter to the brewer, because it has the biggest effect on mash performance. Alkalinity is the concentration of soluble compounds in the water that can neutralize acids. The major chemicals responsible for alkalinity in brewing water are bicarbonate ions (HCO3¯) from dissolved salts such as calcium bicarbonate (Ca(HCO3)2), sodium bicarbonate (NaHCO3), and magnesium bicarbonate (Mg(HCO3)2); and to a lesser extent carbonate (CO32¯) from dissolved salts such as calcium carbonate (CaCO3) and magnesium carbonate (MgCO3).
Alkalinity versus pH
pH measures the amount of hydrogen ions dissolved in water; while alkalinity measures the amount of dissolved alkalis (bicarbonates/carbonates of calcium, magnesium, or sodium) in the water. Therefore, by definition, pH measures one thing, while alkalinity measures another.
Units of Measurement of Alkalinity
Electrical conductivity (EC, also known as conductivity or soluble salts) is a term used to measure the total concentration of salts in irrigation water. A salt is a combination of positively charged elements (cations) and negatively charged elements (anions). The most common cations of interest in water are calcium (Ca2⁺), magnesium (Mg2⁺) and sodium (Na⁺); the most common anions are bicarbonate (HCO3¯), chloride (Cl¯) and sulfate (SO42¯).
Measuring Alkalinity
There are a number of options available to measure alkalinity, and they vary in ease, accuracy and price. The simplest method is to use alkalinity test strip kits and dip the test strip in a sample of water and wait for the coloration of the strip to indicate the approximate alkalinity concentration.
Residual Alkalinity
The other concept used in describing the alkalinity of water is residual alkalinity which is of particular importance in correct adjustment of pH. Fundamentally, residual alkalinity combines in a single term the relative levels of the two key determinants of pH in water, namely the total alkalinity (i.e., level of alkaline substances, notably bicarbonate, as determined by titration) and the level of hardness (as determined from the level of the calcium and magnesium). Paul Kolbach (1953) observed that in mashes consisting of pale malt, 3.5 mEq/L of calcium could neutralize 1 milliequivalent/L of water alkalinity.
Adjusting Residual Alkalinity. Addition of acid to water, or to the mash containing the water, is the most direct way to counteract alkalinity in a water supply. Lactic, phosphoric, and sulfuric acids are suitable and commonly used for this purpose (Section 5.4). The use of phosphoric acid (H3PO4) is commonly used. The phosphate ion is useful in the brewing process and is even produced naturally by the mashing of malt.
Alkalinity versus Hardness
Alkalinity and water hardness are fairly similar—essentially, they both come from sources in nature. Water moves through rocks (and picks up minerals as it does so) on its way to rivers and lakes.
Water Hardness
Water hardness in water is primarily the result of concentrations of calcium and magnesium. Other ions that produce hardness include iron, manganese, strontium, barium, zinc, and aluminum, but these ions are generally not present in significant quantities. Therefore, total hardness is usually defined as the sum of magnesium and calcium hardness in milligrams per liter (mg/L), as calcium carbonate (CaCO3).
Carbonate Hardness
Carbonate hardness is the portion of total hardness present in the form of bicarbonate salts [Ca(HCO3)2 and Mg(HCO3)2] and carbonate compounds (CaCO3 and MgCO3).
Non-Carbonate Hardness
Non-carbonate hardness is the portion of calcium and magnesium present as noncarbonate salts, such as calcium sulfate (CaSO4), calcium chloride (CaCl2), magnesium sulfate (MgSO4), and magnesium chloride (MgCl2).
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