This method describes how to determine the true color of water by means of spectrophotometry.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
The color of water is determined by measuring the absorbance at a minimum of three wavelengths at various points across the visual spectrum:
λ1 = 436 nm (obligatory), λ2 = 525 nm, λ3 = 620 nm (for λ2, λ3 minor deviations are permitted). If necessary, measurements at additional wavelengths must be carried out.