In a small saucepan over medium-high heat, combine all of the ingredients (starting with the ketchup and ending with water). Whisk together then bring to a boil and reduce heat to a simmer. Allow to simmer for about 15-20 minutes, or until the liquid has reduced and a thick sauce forms. Set aside to cool.Once BBQ sauce has fully cooled, transfer it to a glass jar and seal with a lid. Refrigerate for up to 3 weeks.