The quality of water destined for human consumption has been treated as a m
ultivariate property. Since most of the quality parameters are obtained by
applying analytical methods, the routine analytical laboratory (responsible
for the accuracy of analytical data) has been treated as a process system
for water quality estimation. Multivariate tools, based on principal compon
ent analysis (PCA) and partial least squares (PLS) regression, are used in
the present paper to: (i) study the main factors of the latent data structu
re and (ii) characterize the water samples and the analytical methods in te
rms of multivariate quality control (MQC). Such tools could warn of both po
ssible health risks related to anomalous sample composition and failures in
the analytical methods.