This part of ISO 22282 establishes requirements for ground investigations by means of infiltrometer tests as part of geotechnical investigation services in accordance with EN 1997-1 and EN 1997-2. It applies to the in situ determination of the water permeability of an existing geological formation or of treated or compacted materials. The infiltrometer test is used to determine the infiltration capacity of the ground at the surface or shallow depth. It is a simple test for determining the permeability coefficient. The method can be applied using either steady-state or transient conditions, in saturated or unsaturated soils. The principle of the test is based on the measurement of a surface vertical flow rate of water which infiltrates the soil under the influence of a positive hydraulic head. Surface infiltration devices include single and double-ring infiltrometer designs of the open or closed type. The measurement devices and measurement procedures are adapted to different ranges of permeability. Open systems are adapted to permeability ranges from 10−5 to 10−8 m/s and closed systems for permeability lower than 10−8. Depending on the environmental conditions and the water permeability of the soil, a duration of a few minutes to a few days is needed to run the test. This part of ISO 22282 defines the terminology and the measured parameters. It specifies the required characteristics of the equipment, defines the procedures of the tests relating to the different measurement techniques and specifies the tests results. It is applicable to: — civil engineering projects; — hydrogeology studies; and — waste storage.