The 'Tool for the Analysis of the Production of drinking WATer' (TAPWAT) model has been developed for describing drinking-water quality in integral studies in the context of the Environmental Policy Assessment of the RIVM.
The model consists of modules that represent individual steps in a treatment process, so that different treatment processes can be constructed. The treatment steps included in TAPWAT are used mainly in systems for the treatment of surface water. The current version of TAPWAT described in this report consists of modules based on removal percentages and on process or semi-empirical modelling. Stochastic modelling using beta-distribution has been worked out for two treatment steps and seems to be a promising technique; however, the availability of data for individual treatment steps is a disadvantage.In general, this combination works out fairly well in the model structure developed for TAPWAT.
The model must be able to cover, at least for pathogens, the pathway from water source to infection risk for the public. The parts of the puzzle are present, but the puzzle still has to be laid. The model is as yet only suitable for operation by experts. A plan of action is recommended in which the existing and missing modules, compounds and micro-organisms of interest will be prioritised and the necessary validation of the model described. This plan of action should be implemented to improve the current TAPWAT version and make it suitable for assess public health risks.