A potable water system comprises a supply line and a water-purification device incorporated thereinto. The spiral probe is embedded in an insulating substrate in a manner that permits resilient deformation thereof in accordance with a shape of the solder ball. When the backup MBR cannot normally be read or is improper, the MBR is copied to the backup MBR. Furthermore, the network protocol may be adapted to include a priority parameter in SMSs. A switching device may receive the switch-off signal and separate the arrester from an electric circuit, the switching device and arrester being arranged in a physically separate manner from each other.