An assembly for preparing mineral water in situ, including a container filled with a mineral concentrate and a dosing device connected to the holder for dispensing the concentrate from the container in a dosed manner, the dosing device being provided with a housing including an inlet, an outlet, a liquid flow path, a pump, and a magnetizable or magnetic operating element. The apparatus includes a memory module having a set of paired memory devices including a first memory device to store a first section of a data word and a second memory device to store a second section of the data word when used in failure free operation. A reducing gas is bubbled through the liquid as it is subjected to cavitation to affect the reductive decomposition of the metal compounds.