What is a brew? A brew implies an alchemical transformation of a solid of some sort, into a liquid of some sort. Beer is brewed, and little yeasties change the sugars into alcohol in your stein. Or you can make a simple cup of tea, and the heat and contact with water extracts the active ingredient of an herb, or the tasty parts, into the beverage in your cup.
So this is a broad category, and one of the main studies of the Potioneer. But to broaden the category further, you could include any decoction or infusion of an herb (or formula of herbs) into any liquid menstruum, including water, alcohol, and vinegar. Some might be intended for consumption, but others might be used for other spell or ritual purposes. For example, my Four Thieves Vinegar is a brew of herbs extracted into Vinegar that is not meant to be drunk. But herbalists make Fire Ciders which are Vinagar based brews that are dosed for internal consumption to prevent or treat infections. You can make a tincture of Benzoin which is used to preserve salves and lotions but would not be good to drink. This is an example of an alcohol-based brew that you would not drink. However, you can use Vodka or grain alcohol (because alcohol is an excellent solvent) to extract the active ingredients from a magickal or medicinal herb. You could drink this sort of brew and enjoy both the spirits of the herbs and the intoxication of the alcohol. You can make infusions or decoctions of edible herbs to drink as teas, or you could make a "tea" of toxic or bad-tasting herbs to use for nonconsumptive purposes, like Mandrake for your scrying bowl, or Alkanet for your exorcism asperger. A simmering pot, where you simmer herbs in a pot of water to fragrance the witches' kitchen, would be another example of a nonconsumptive brew.
The brews on this page are to make teas out of. They are magickal in nature and non-toxic when prepared as herb teas. Some of them can be steeped into alcohol for a stronger brew. You could also use some imagination to find excellent non-consumptive uses for these brews. For example, the Full Moon Brew would be excellent to wash or consecrate your crystal bal or scying mirror.
For more detailed information and instruction for Kitchen Witch brew techniques, refer to my article, "Perfect Cuppa Brew."