This International Standard provides guidance on the principles behind, and main methods for, the evaluation of sites, soils, and soil materials in relation to their role as a source of contamination of groundwater and their function in transporting, degrading and transforming contaminants. It identifies and lists relevant monitoring strategies, methods for sampling, soil processing and analytical methods. This International Standard is applicable to the evaluation of the impact of contaminants on groundwater in relation to - drinking water quality, - irrigation water quality, - industrial use, - natural base flow.