Lime/Calcium buildup on steam generator components is the nature of steam. As the water boils to produce steam, it leaves the impurities behind. These impurities then attach to the internal components and can cause equipment failure. Add a water purification system to your installation and follow the manufacturers routine maintenance instructions. This image depicts lime. It shows the heating element broken into 3 pieces and lime that was removed from the water tank. The heating element broke down due to the lime on the liquid level switch and water feeder float sending a false sense of the tank being filled. Since the tank was really empty, the element was not submersed.