This European Standard specifies general requirements for installation (including ancillaries) methods for checking the functionality during normal operation and requirements for maintenance and repair to prevent and repair failures of water conditioning devices inside buildings for the treatment of drinking water. This European Standard concerns devices which are permanently connected to the water distribution system in a building at the point of entry (downstream from the delivery point of the mains supply) and/or at the point of use. NOTE Influence of the water quality on the distribution system downstream of the device is not covered by this European Standard but is covered by documentation for specific devices.