Schedule 40 Gray PVC used as Drain

Can gray pvc be used for water drainage if schedule 40? I believe 40 is the standard for drainage correct me if wrong.

You’ll need to wait for the official US ‘Code’ replies, but in the meantime…

Polyvinyl chloride (PVC) is a combination of plastic and vinyl that is used to make PVC pipes. These popular types of pipes are commonly used in plumbing as an alternative to more expensive copper piping. PVC is also used to produce electrical conduit. While regular PVC and electrical conduit PVC are both made from the same type of plastic, they are not the same thing, nor should they be used for the same applications. Each should only be used as it is intended and not interchangeably.


The piping in use that the OP is referring to is in a WASTE scenario, so, it is NOT under pressure so is a non-issue!

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I’m not an expert on PVC, but I believe the term schedule 40 has to do with the thickness of the walls of the PVC pipe, not necessarily the proper usage.


Yes, but the Sch.40 comes into play when under pressure and temperature considerations (140f).
Again, not an issue in a typical waste application.


You need to read the whole thing, not just what may fit your agenda.

Because plumbing PVC is used in applications that have pressure to consider, the added thickness ensures that the pipe is strong enough to resist bending and that it will remain undamaged and intact. Conduit PVC isn’t required to withstand as much pressure, so it isn’t made with walls that are thick.

I would think that since it is used underground for laterals at times 5-8’underground, that would be considered pressure.

All of the above differences indicate that while PVC plumbing pipe and PVC electrical conduit are similar, they are not appropriate for each other’s applications. They have been manufactured to serve different purposes.

P2503.5.1 Rough Plumbing

DWV systems shall be tested on completion of the rough piping installation by water or, for piping systems other than plastic, by air, without evidence of leakage. Either test shall be applied to the drainage system in its entirety or in sections after rough-in piping has been installed, as follows:

  1. Water test. Each section shall be filled with water to a point not less than 5 feet (1524 mm) above the highest fitting connection in that section, or to the highest point in the completed system. Water shall be held in the section under test for a period of 15 minutes. The system shall prove leak free by visual inspection.
  2. Air test. The portion under test shall be maintained at a gauge pressure of 5 pounds per square inch (psi) (34 kPa) or 10 inches of mercury column (34 kPa). This pressure shall be held without introduction of additional air for a period of 15 minutes.
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You need to take your own advice… and add in ‘situational awareness’ and ‘comprehension’ to that list!!

So is the general consensus that waste piping usage is acceptable for gray pvc if labeled as such in the pics? I didn’t think drain waste would be under pressure but the main drain going underground was also gray.