In 3-quart saucepan combine sugar, corn syrup and water. Cook over low heat, stirring occasionally, until sugar is dissolved and mixture comes to a full boil (20 to 30 minute). Add butter; continue cooking, stirring occasionally, until candy thermometer reaches 280 °F or small amount of mixture dropped into ice water forms a pliable strand (80 to 90 minute). Stir in peanuts; continue cooking, stirring constantly, until candy thermometer reaches 305 °F or small amount of mixture dropped into ice water forms a brittle strand (12 to 14 minute). Remove from heat; stir in baking soda. Pour mixture onto 2 buttered cookie sheets; spread about 1/4-inch thick. Cool completely; break into pieces.