The fluorescence characteristics of natural organic matter in a groundwater based drinking
water supply plant were studied with the aim of applying it as a technique to identify
contamination of the water supply. Excitationeemission matrices were measured and
modeled using parallel factor analysis (PARAFAC) and used to identify which wavelengths
provide the optimal signal for monitoring contamination events. The fluorescence was
characterized by four components: three humic-like and one amino acid-like. The results
revealed that the relative amounts of two of the humic-like components were very stable
within the supply plant and distribution net and changed in a predictable fashion
depending on which wells were supplying the water. A third humic-like component and an
amino acid-like component did not differ between wells. Laboratory contamination
experiments with wastewater revealed that combined they could be used as an indicator of
microbial contamination. Their fluorescence spectra did not overlap with the other
components and therefore the raw broadband fluorescence at the wavelengths specific to
their fluorescence could be used to detect contamination. Contamination could be detected
at levels equivalent to the addition of 60 mg C/L in drinking water with a TOC concentration
of 3.3 mg C/L. The results of this study suggest that these types of drinking water systems,
which are vulnerable to microbial contamination due to the lack of disinfectant treatment,
can be easily monitored using online organic matter fluorescence as an early warning
system to prompt further intensive sampling and appropriate corrective measures.