This recipe is taken from The Farm House Cookbook by Susan Herrmann Loomis:
1 cup sugar*
7 tablespoons apple cider vinegar
1 tablespoon grated fresh ginger or 1 teaspoon ground ginger
1/4 cup freshly squeezed lemon juice
8 cups cold water
Mix all ingredients together in a large bottle or jar, and shake thoroughly. Refrigerate before drinking. Makes 2 quarts. *You can swap the sugar for honey or maple syrup, if you like. Just heat the switchel before pouring it in the jar so that the sweetener dissolves fully.