Open and drain the can of water chestnuts. Add to a medium bowl. Add the 3 Tbsp soy sauce and allow to marinate at least 15-30 minutes, up to overnight. Give it a stir once or twice to make sure they're evenly coated.
Slice each strip of bacon into thirds (or halves depending on the length of your bacon). Wrap each water chestnut in bacon and fasten with a toothpick. Make sure to reserve the soy sauce.
Arrange the wrapped water chestnuts in an oven safe 8"x8" pan. Bake for 30 minutes at 350°. Exact timing may depend on the thickness of your bacon. You want it to start getting cripsy, but make sure it doesn't burn, as it will go back in the oven later.
Meanwhile, in the bowl with the reserved soy sauce, add ¾ cup brown sugar and ½ cup ketchup and stir until evenly combined.
Remove water chestnuts from the oven after 30 minutes and drain the grease. Add back to the same pan, and using a brush or spoon, coat the water chestnuts with the glaze.
Bake for an additional 20-30 minutes or until brown and crispy.