Wrap 1/2 strip of bacon around each water chestnut; secure with toothpicks.
Place chestnuts on a wire rack that is placed on a baking sheet. You will have grease collection, so be sure the baking sheet or pan has sides. If you don't have a wire rack, use foil on a baking sheet.
Bake at 350 degrees Fahrenheit for 30 to 55 minutes or until desired crispness. I like my bacon very crispy, so I bake close to 55 minutes.
To make the sauce, add ketchup, brown sugar, and soy sauce to a medium bowl. Whisk to combine.
Pour sauce evenly into a 9x13 glass baking dish.
Arrange the bacon-wrapped water chestnuts to the glass baking dish, gently arranging them in the sauce, neatly in rows. After they are all arranged, use a pastry brush to gently brush some of the sauce onto the tops of the water chestnuts.
Bake an additional 25 to 30 minutes.
Notes
Initial bake time really depends on how you enjoy your bacon. Keep an eye on it and bake a little longer if you want it crispier!