This International Standard specifies a method for the determination of chromium(VI) in drinking water in mass concentrations between 2 ?g/l and 50 ?g/l. For the determination of higher concentrations, the sample is diluted prior to analysis. The method may also be applied to weakly polluted ground and surface water, provided the matrix does not contain interfering reducing agents. This method has not been verified for estuarine water and seawater, so the user is responsible for the validation of the method for these matrices. The photometric determination of chromium(VI) in waste water is carried out according to ISO 11083, Water quality — Determination of chromium(VI) — Spectrometric method using 1,5-diphenylcarbazide