This standard pertains to geomembrane materials supplied in sheet form for lining, covering, or lining and covering potable water reservoirs. The successful application of this standard is dependent on an appropriate site evaluation, design, material selection, construction, as well as operations and maintenance. This standard includes requirements for material properties, fabrication, and installation. AWWA Manual M25 complements this standard by providing supplemental definitions of terms, as well as design, installation, operation, and maintenance considerations for geomembrane systems. Major revisions made to this edition of the standard include: standard title was updated; Section 3, Definitions, was updated; Sec. 4.5.5, Repairs, was updated; and, Table 2, Quality-control testing, was updated.