Lay out silicone sheet/mat to pour peanut brittle onto.
In a large skillet mix the sugar, syrup, and water together. Cook at a medium-high heat (#7), stirring regularly. Heat until the mixture has a hard ball consistency. Heat to 265 degrees F, or until a small amount of syrup dropped into cold water forms a rigid ball. If you don't own a candy thermometer, occasionally hold spoon above mixture, allowing it to drip off spoon. When mixture is at hard ball stage, it will 'hair' off the spoon when falling, looking like a clear spider web.
Once mixture is at hard ball consistency, add raw peanuts, butter and vanilla. (The peanuts may pop a little.) When mixture starts to turn a light clear-brown, as if it's starting to burn, remove from stove. Add soda and stir. Mixture will foam up.
Pour mixture onto silicone sheet/mat as one big piece. Break into smaller pieces once cooled.