Ask Me Help Desk - Why use copper for DWV?

Hello,

Something's been nagging me for a while. Several different kinds of material are used for DWV systems, each with its own pros and cons.

PVC (and I guess ABS) is inexpensive and easy to work with, but is not allowed by all codes, and is a lot noisier (I've been to a few houses where some idiot plumber ran a 3" PVC toilet stack right through the middle of the living room/dining room area, resulting in a rather inelegant situation whereby you're entaining company, and everyone in the room hears the wastewater running inside the wall when the upstairs toilet is flushed).

Cast iron is quieter and is more universally accepted, but costs much more and is quite difficult to work with (especially hubbed lead-and-oakum joints).

And then there is copper.

This always bothers me. Who the heck would want to use copper for DWV? It costs a FORTUNE - sometimes even more than cast iron, corrodes/wears out more quick than PVC, is not much easier to install than PVC, and does the same job as cast iron as far as codes requiring non-plastic are concerned. Am I missing something here? Is there some reason why copper might be better than cast iron, PVC, or ABS?

Confusedly yours,
Moishe

Moshie,
Back when I was plumbing new construction we used cast iron for drainage. However we used copper for stub outs and drain arms from sinks and lavatories. The times they are a changing! Unless local codes force us to use cast iron and copper we rough out our new construction with PVC for the drainage. And more and more homes are being water piped with CPVC or Pex systems. We changed our drainage from ABS to PVC back in the 70's. PVC was more ridgid. You are 100% correct. PVC is much better then copper. Regards, tom

Quote:

Originally Posted by speedball1

You are 100% correct. PVC is much better then copper. Regards, tom

Thank you. But as you can see from the subject line, my main concern was copper. I think you answered that with the second line, "However we used copper for stub outs and drain arms from sinks and lavatories." Do you mean to tell me that that's all copper is used for in drainage? i.e. those 10' lengths of copper I see at the store marked "DWV" are only used for stub-outs, and not for actual sewer/vent stacks and branches?

My house was built in 1970 in an area with no building inspection. Every bit of the original plumbing from the pressure tank to the septic tank was copper. Copper is easier to work with than cast iron. Some people are convinced copper means quality, and likely are still insisting on it.

Go to any place that sells plumbing supplies and you will see a better selection of gate and globe valve than the more functional ball valves. Technology changed in the late 70's making ball valves more available. Another 50 years, and they may catch on.

Quote:

Originally Posted by PalmMP3

Thank you. But as you can see from the subject line, my main concern was copper. I think you answered that with the second line, "However we used copper for stub outs and drain arms from sinks and lavatories." Do you mean to tell me that that's all copper is used for in drainage? i.e. those 10' lengths of copper I see at the store marked "DWV" are only used for stub-outs, and not for actual sewer/vent stacks and branches?

Moshie,
I broke into plumbing in the 40's in Wisconsin. At that time, in my area, we used 4" cast iron for the main sewer and vent and 1 1/2" & 1 1/4" galvanized pipe for most everything else. Then in the 50's we moved to Florida where we used 4,3 and 2" cast iron for drainage systems. We used DWV copper for stubouts and to arm out for sinks and lavatorys. We now use PVC. Since I have been answering questions I have been sent photos of homes like Labmans that had the drainage completely done in copper. But I have never worked in a area that used copper exclusively for drainage. Itwould seem to me that the high cost of copper would not make doing the drainage in copper very cost effective. Hope this answers your question. Tom

Quote:

Originally Posted by speedball1

Itwould seem to me that the high cost of copper would not make doing the drainage in copper very cost effective.

Yeah, I know - that's exactly what I said in my original post: why would anybody waste so much money using copper for DWV, if it has no obvious benefits over other materials, such as cast iron or PVC...

Do you agree copper is easier to use than cast iron, or at least was in the days of hubs, oakum and lead? There is a perception metal is better than plastic in any application. After all aren't you the one that says NYC still requires copper? I am not saying copper is better. I am just saying it some people insist on using metal, good reason or not. There may be a matter of slow to change codes. Even without building inspection, the contractor may not have made a gross violation of code that wouldn't be hidden in my house. By earlier adoption of plastic drain pipe, Florida may have enjoyed lower cost housing. This is not a rational world.

I use PVC/CPVC every chance I get on my projects. Cheap, readily available, easy to work with, and I never have leaks.