Deaerated Water. Naturally occurring water contains a high concentration of oxygen (up to 10–12 ppm dissolved oxygen), and as oxygen is detrimental to the flavor stability of beer, any water that comes into contact with fermented beer should be “deaerated,” or more precisely, deoxygenated.

In the brewing process deaerated water is preferred, if not required, for the following uses:

• Diatomaceous earth (kieselguhr) filtration: to suspend the DE for the filtration process and to precede and follow the beer through the filter. See diatomaceous earth.

• Production of “gravity liquor,” the deaerated and carbonated water used for diluting the beer in high gravity brewing. See high gravity brewing.

• Pushing of beer from tank to tank, to filters, and filling machines

• Suspension of all additives added to finished beer

• All final rinses in cleaning processes for tanks and other equipment used for fermented beer

The methods used for deaerating water vary from very simple to quite complicated and expensive. The simplest is boiling the water, as oxygen has very low solubility in hot water. “Scrubbing” of the water with oxygen-free CO2 or nitrogen is another method, and finally applying a vacuum to water trickling over a large surface (often in a hollow tube filled with small “fillers”) can also be applied. These processes may be repeated or combined to achieve the specified oxygen content required, often 0.01 ppm or lower.

See also water.