This standard describes polyethylene (PE) pressure pipe and tubing made from material having standard PE code designations PE 2606, PE 2706, PE 2708, PE 3608, PE 3708, PE 3710, PE 4608, PE 4708, and PE 4710 and intended for use in potable water, reclaimed water, and wastewater service. Polyethylene pipe ranges in nominal size from 1/2 in. (13 mm) through 3 in. (76 mm) and conforms to the outside diameter (OD) dimensions of iron pipe sizes (IPS) or to the inside diameter (ID) dimensions of IPS pipe. Polyethylene tubing ranges in size from 1/2 in. (13 mm) through 2 in. (51 mm) and conforms to the OD dimensions of copper tube size (CTS). Included in this standard are criteria for classifying PE plastic pipe materials, a system of nomenclature for PE plastic pipe, and requirements and test methods for materials, pipe, and tubing. Methods of marking are given. This edition of ANSI/AWWA C901 is a comprehensive update and includes significant revisions and changes to all sections of the standard. Major changes made to the standard in this revision include the following: Sec. 1.1 Scope - removed material designations made obsolete by changes to ASTM D3350 and replaced with current and new material designations; Section 2 References - added seven ASTM standard references, reference to AWWA manual M55, and reference to NSF/ANSI 61, deleted references to ISO 161 and NSF/ANSI 14; Section 3 Definitions - deleted definitions for bloom, design factor, and working pressure; revised definitions for dimension ratio, hydrostatic design basis, hydrostatic design stress, pressure class, and surge pressure allowance; Section 4 Requirements - Sec. 4.1 clarified permeation statement, Sec. 4.2 revised material requirements to be consistent with new material designations, revised Table 1, revised potable water certification to NSF/ANSI 61; Sec. 4.3 added toe-in, added special sizes, revised elevated temperature sustained pressure test, replaced Table 8 with new Table 2, replaced Tables 2, 3, 4, 5, 6, 7, and 9 with new Tables 3, 4, 5, 6, and 7, added length tolerance, added elongation at break test, deleted Sec. 4.4; Section 5 Verification - Sec. 5.1 revised, 5.2 revised, deleted Sec. 5.2.2 (replaced with Sec. 4.3.9), Sec. 5.3 added 5.3.1, 5.3.2, 5.3.4, 5.3.6, and 5.3.7, revised Sec. 5.3.3 and 5.3.5; Sec. 5.4 revised, Sec. 5.5 revised, Sec. 5.6, revised Sec. 5.6.2, 5.6.3, 5.6.4, and 5.6.5; and, Section 6 Markings and Delivery - Sec. 6.1 revised 6.1.2, 6.1.3, and 6.1.4, added 6.1.5, Sec. b. ec. 6.2 revised 6.2.1, deleted Sec. 6.2.2, and Sec. 6.3 revised.