is heated brewing water, “liquor” being the traditional name given to the water that will later become beer in the brewing process. All other water used in the brewery, such as water used for cleaning, is simply called “water.” The term “hot liquor” is widely used in the UK and the United States. Generally hot liquor is used as “foundation liquor” preparing the mash tun for malt, “strike liquor” for mixing with the malt, and “sparge liquor” to sparge over the mash or lauter bed. Breweries using corn or rice would also mix hot liquor with these grains in the cereal cooker. Hot liquor is heated to between 110°F and 170°F for mixing with malt to form the mash and as high as 180°F for sparging. The hot liquor resides in the hot liquor tank until needed in the mash tun, lauter tun, or cereal cooker.

Filtering the incoming liquor to remove contaminants and chlorine is common. Less common are procedures to settle out unwanted contaminants such as silt or iron. Sometimes minerals are added, especially gypsum, to harden the liquor. See burtonization. The mineral constituents of the hot liquor greatly influence the qualities of the resulting beer. The mineral content will affect the beer flavor and sometimes hard water needs to be softened to become hot liquor that will produce beer with acceptable flavors. Beyond the simple taste desirability lies the need for the water to provide sufficient minerals for brewing chemistry and yeast nutrition.

See also water.