This document specifies the characteristics of geosynthetic barriers, including polymeric geosynthetic barriers, clay geosynthetic barriers and bituminous geosynthetic barriers, when used as fluid barriers and separation layer in the construction of tunnels and associated underground structures, and the appropriate test methods to determine these characteristics. The intended use of these products is to control the leakage of fluid through the construction. 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 (AVCP) of the product to this European Standard including factory production control procedures. This document defines characteristics to be considered with regard to the presentation of performance. This document does not cover applications where the geosynthetic barrier is to be in contact with water that has been treated for human consumption. NOTE – Where potable water is or can be in direct contact with the product, other relevant standards, requirements and/or regulations can be considered for the design.