This document specifies the relevant characteristics of clay geosynthetic barriers (GBR-C) as well as multicomponent geosynthetic clay barriers (e.g. a GBR-C with a polymeric or bituminous geosynthetic barrier attached to it), when used as fluid barriers in the construction of underground structures (other than tunnels and associated structures), and the appropriate test methods to determine these characteristics. If in a multicomponent GBR-C, the GBR-P or GBR-B is the predominant long-term hydraulic barrier than the appropriate standard should be used. The intended use of these products is to control the leakage of fluid through the construction wall. This document is not applicable to geotextiles or geotextile-related products as defined in EN ISO 10318 1. This document provides for the assessment and verification of constancy of performance of the product to this European Standard and for factory production control procedures. This document defines requirements to be met by manufacturers and their authorized representatives with regard to the presentation of product properties. This document does not cover applications where the geosynthetic barrier is to be in contact with water that has been treated for human consumption. Where potable water is or may be in direct contact with the product, the designer should also refer to other relevant standards, requirements and/or regulations.