This part of ISO 5667 provides guidance on the sampling of groundwater. It informs the user of thenecessary considerations when planning and undertaking groundwater sampling to survey the quality of groundwater supply, to detect and assess groundwater contamination and to assist in groundwaterresource management, protection and remediation. It does not cover sampling related to the day-today operational control of groundwater abstractions for potable purposes. The guidance includes sampling of groundwater from both the saturated (below water table) zone and the unsaturated (above the water table) zone.