Most solution concepts for the thermal treatment of water and other materials are based on a multi-effect vacuum distillation which enables heat to be used efficiently at low temperatures. Due to the vacuum, the technology works at low boiling temperatures and energy can be recovered from within the system in several pressure stages. This means that energy is used several times, lowering the specific energy requirements significantly. The boiling temperature in the vacuum is also considerably lower so that the energy requirements can be met with simple solar thermal collectors or by using waste heat from approx. 60 °C.