The process comprises avoiding the hydrogen formation by an active pH-stabilization during the use of elementary metals for groundwater rehabilitation, where the change in the pH-environment takes place in a metal-specific manner and with environmentally-compatible materials, which are introduced as solid material and achieve a long-term effect. By the change in the pH-environment, the efficiency of the metal use is obviously increased by avoiding loss of active metal and avoiding formation of disruptive corrosion products and the hydrogen formation, which lead to clogging the subsurface.