Passive sampling has been developed to obtain, at lower cost, more representative evaluations of the average concentrations of contaminants in aquatic environments. An innovative silicone-based passive sampler (named PACSiR, for Polar Apolar Composite Silicone Rubber) was designed to address sampling, detection and quantification of a wide range of organic contaminants (native or metabolites) present at ultratrace levels in waters. The PACSiR passive samplers, of small size (2 cm length), were applied in different aquatic media (surface or underground waters), typically for periods of 1 week, to evaluate the contamination by a wide range of pesticides and metabolites. They were also tested for their capacity to monitor several hormones and pharmaceuticals. The nature and mass of contaminants sorbed on the passive samplers exposed in situ were used as qualitative or comparative measures, to highlight the presence of compounds or to easily assess trends and gradients of contamination in aquatic environments. For quantitative purposes, the estimation of the average concentration of contaminants in water required the prior determination of kinetic parameters (sampling rate, equilibration time) through laboratory experiments. We demonstrated that this reactive, single-use and low cost passive sampler can be used for multiple research or operational purposes, thanks to the different levels of data acquisition, from qualitative to quantitative approach.