Reagents’ consumption depends on the unit’s reliability, deposits on the heat surface and the final product of the wastewater treatment. The reagents’ list and consumption are defined in line with priority goals, such as the unit’s reliability and operation without scaling. In certain cases, a higher consumption of reagents is required to obtain low-hazard waste and products for sale. There are low-reagent or reagent-free methods to reduce the water hardness, but often they are incapable of resolving a complex task, unreliable and require a more cautious application.