This part of ISO 22475 deals with the technical principles of sampling of soil, rock and groundwater, and with groundwater measurements, in the context of geotechnical investigation and testing, as described in EN 1997-1 and EN 1997-2. The aims of such ground investigations are: a) to recover soil and rock samples of a quality sufficient to assess the general suitability of a site for geotechnical engineering purposes and to determine the required soil and rock characteristics in the laboratory; b) to obtain information on the sequence, thickness and orientation of strata and joint system and faults; c) to establish the type, composition and condition of strata; d) to obtain information on groundwater conditions and recover water samples for assessment of the interaction of groundwater, soil, rock and construction material. The quality of a sample is influenced by the geological and hydrogeological conditions, the choice and execution of the drilling and/or the sampling method, handling, transport and storage of the samples. This part of ISO 22475 does not cover soil sampling for the purposes of agricultural and environmental soil investigation. NOTE 1 Soil sampling for these purposes is to be found in ISO 10381. Water sampling for the purposes of quality control, quality characterisation, and identification of sources of pollution of water, including bottom deposits and sludges is not covered. NOTE 2 Water sampling for these purposes is to be found in ISO 5667.