A sparge tank is essentially the container where the brewing water is carefully heated to the required mash temperature. Advanced and experienced all-grain brewers use an HLT (Hot Liquor Tank) to heat their strike and brew water. Brewing salts are added to the source water while it is in the Hot Liquor Tank. The sparge tank can be heated from an external source such as LP Gas or even a wood-burning fire. Modern Hot Liquor Tanks are extremely advanced and feature internal heating components, built-in thermostats, and sensors to carefully monitor the tank.