SimpleTreat is an assessment tool for the fate of substances in waste water treatment plants. The tool considers the most important processes like volatilization, mixing, adsorption and degradation.


SimpleTreat 4.1 is an exposure and emission model developed to estimate chemical emission from sewage treatment plants and exposure in surface water within the framework of risk assessment of chemicals. The current version is a revision of SimpleTreat 4.0.9, please see the release note for details. SimpleTreat 4.0 and 4.1 are both updates of SimpleTreat 3.1, which supported the chemical act 30 years ago in the Netherlands and later in the European Union (EU European Union (European Union)). The revision from v4.0 to v3.1 was necessary to account for more recent scientific insights with respect to behavior of chemicals in domestic sewage and activated sludge.


Release notes

Release note to SimpleTreat 4.0.9

Release note to SimpleTreat 4.1.0



Beside the use as a research tool, SimpleTreat 4.1 is used to assess substances in accordance to REACH (Registration, Evaluation, Authorization and restriction of Chemicals) and other regulations of substances in the EU, such as biocides, medicines and plant protection products.

Model and documentation

SimpleTreat 4.1 is offered as a Windows application compatible with versions of Microsoft Windows 10 and higher. The technical background of the model is described in an RIVM Report. The application of the model in EU substance regulations is described in an UBA report.


The SimpleTreat Windows application is freely available for non-commercial use. The application can be downloaded here.

There is no helpdesk to answer questions of users. However, we welcome your comments on the program and its functioning at

SimpleTreat 4.1 screenshot