The standard applies to all types of water. The detection limit depends on the device used; In general, copper contents can be determined from 0.01 mg/l. For copper contents lower than 0.1 mg/l, use of graphite furnace technology is recommended, see NEN 6454.
NEN 6451-1980 history
1980NEN 6451-1980 Water - Determination of copper content by atomic absorption spectrometry (flame technique)