A number of novel sampling devices for level-accurate sampling of groundwater from existing water wells is to be tested in various aquifers, unconsolidated sand and gravel, fissured sandstone and karstic limestone. the quality of samples collected by the novel samplers will be compared with that of samples taken from conventional well-separated screens in nearby wells and validated by the combined use of modelling, laboratory studies, and field experiments. The objective is to develop sampling techniques that are much more economical and rapid than hitherto applied techniques, the novel samplers being easily installed, removed, and possibly repaired, at the well to be examined. To make these methods fully operational they must be evaluated under controlled conditions in several hydrogeological environments and in the laboratory. The designs that are tested in parallel are: - separation pumping (Geological Survey of Denmark), - In-Line-Packer system (university of Stuttgart), - fire-hose sampler (Geological Survey of Denmark), - baffle flow separation (Geological Survey of Denmark).