A new method for the water source apportionment of the Barcelona (Spain) water distribution system is proposed. The method is based on the combined use of UV spectrophotometric measurements in the wavelength from 190–230 nm, and multivariate data analysis using the Partial Least Squares (PLS) chemometric method. From the differences in the organic matter content of the different water sources and of their corresponding UV spectral features, PLS was able to determine the relative amounts of the two main river water sources in samples of tap water from the different locations of the Barcelona city water distribution system. The extension of the method to determine the relative amounts in water blends, prepared from samples from five water treatment plant sources of the same city’s distribution system, required the combined use of some other parameters. In particular, the distinction and apportion of the water coming from a desalinisation plant could be successfully achieved once concentrations of Boron were included in the analysis.
Keywords: PLS, source apportionment, UV, water distribution system