The standard applies to drinking and surface water. The determination is only possible in clear water. Note The naturally occurring color comes from, among other things, humic compounds, iron and manganese salts. As a result of contamination, for example by industrial wastewater, the water to be examined may have a color different from the naturally occurring color. Since a proper measurement of the intensity is then not possible, in such cases consult NEN 3235 2.2.
NEN 6413-1979 history
1979NEN 6413-1979 Water - Determination of colourintensity