In this video, Matt Risinger and Jordan Smith have some fun cutting open and examining four old water heaters. Results varied, but the amount of mineral scale in all of the tanks was surprising. Calcium carbonate is the primary component in hot-water-tank scale. There seemed to be more scale at the top of the tanks; however, in the electric tanks, some scale was observed to be flaking off the anodes and settling at the bottom. One tank had close to 3 inches of sand-like deposit. Pretty gross.This demonstration presents a good argument for flushing your water heater periodically, and in areas with especially hard water, using a water-softening or filter system.