The objective of this paper is to present the potential contribution of a relatively recent technique, artificial neural networks (ANNs) in modelling chlorine demand and THM occurrence in drinking water. First, a brief overview of modelling with classical approaches is made for both chlorine demand and THM formation. The ANN modelling approach and the development of models for chlorine demand and THM formation are also described. Finally, a comparison of classical models with ANN models permits the evaluation of the contribution of ANNs and the identification of the conditions in which their application may be useful.