What is C900 pipe? What about C905 pipe?

C900 is the AWWA standard for cast-iron-pipe-equivalent outside diameter polyvinyl chloride (PVC) pressure pipe and fabricated fittings for potable water transmission and distribution, covering nominal pipe sizes from 4 inches through 12 inches. The standard covers three classes of pressure pipe and dimension ratios (DRs):

DR 25 / 165 psi
DR 18 / 235 psi
DR 14 / 305 psi

C900 pipe and fittings must comply with the requirements of the Safe Drinking Water Act. PVC compounds and products must be in compliance with NSF/ANSI 61 certification for potable water service. The C900 standard does not include injection molded PVC fittings. Injection molded PVC fittings are covered in AWWA C907. C900 pipe is delivered in standard laying lengths of 20 feet +/- 1 Inch.

C900 pipe is also suitable for use in waste water force main services.

C905 is a comparable standard for potable water PVC pressure pipe, designed for pipe and fittings with  nominal sizes over 12 inches.