I had a plumber come out the other day to do some work and I offered up some spare PVC that I had leftover from various projects and he told me that it was schedule so-and-so and wouldn't be appropriate/durable for the task I had in mind.

I had never even paid attention to the fact that PVC pipes came in different "Flavors" or schedules and always just grabbed whatever I came upon first that was the right size. Kinda scary thinking about all the DIY projects I have used it on.

So can someone give me a brief summary of the different schedules of PVC pipes available and what each one should be used for?


The schedule is the wall thickness of the pipe (essentially how much pressure it can withstand). Wikipedia has a Nominal Pipe Size Table (and the article goes into the description of the size and the why behind them).

From this article http://www.ehow.com/facts_5575151_difference-between-schedule-schedule-pipe.html:

For a relatively constant pipe outside diameter, the wall thickness varies from Schedule 10 (light) to Schedule 40 (standard weight) to Schedule 80 (extra strong) to Schedule 160 (double extra strong).

Schedule 40 pipe is typically used in construction. However, if a stronger pipe is needed, then Schedule 80 can be used. An example where Schedule 80 should be considered is if the pipe is exposed during construction. The stronger pipe is more resistant to incidental bumping by workers or equipment.

In my house the line that runs out to my irrigation system and the sewer pipe are all schedule 40 (the schedule is usually printed on the pipe).

  • 2
    So could you add to your answer a most common usage scenario for each of the schedule types you mentioned? Is there some kind of code that applies?
    – JohnFx
    Oct 7 '10 at 20:35
  • With sewer and irrigation pipe, you will also see SDR sizing (Standard Dimension Ratio) which is the diameter to wall thickness ratio. The higher the number, the thinner the wall. SDR 35 is a common sewer pipe ratio, some plumbers call it "eggshell" pipe, which is an exaggeration of course, but gives you an idea how thick the walls are. Sch 40 pipe is around SDR 10-20 depending on size.
    – bcworkz
    Feb 4 '13 at 23:16

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