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PVC Pipe vs. Cast Iron Pipe

By
©1993-2012 Tim Carter

        
Summary: PVC pipe and cast iron pipe both have two sides of virtue. Cast iron pipes have been given a false bad image.

Cast iron piping has not given up the ghost. Many homeowners associate cast iron piping with antiquated plumbing that is prone to developing leaks. Often people think that it clogs quite easily. Conversely, many people think that modern plastic PVC plumbing piping is the miracle material. Well, both materials have advantages and disadvantages. Let's talk about both types of pipe and see what you think.

That Old Black Metal

Cast iron piping has been used successfully in plumbing systems for hundreds of years. In fact, in the year 1623 cast iron pipe was installed in the Fountains of Versailles in France. That same piping is still functioning today. Thousands of miles of municipal water and sewer systems use cast iron pipe. The reason is long term durability. Cast iron simply lasts.

Virtually every residential home built prior to 1960 had some form of cast iron piping in its drainage system. The primary drainage stacks or pipes within the walls were constructed of cast iron. The branches off of these stacks which connected to sinks, toilets and tubs often used lead piping or galvanized pipes. Galvanized iron piping is especially prone to clogging. I have personally removed hundreds of these pipes which connected to kitchen or bathroom sinks. In virtually every instance, these pipes were clogged solid.

However, the cast iron stacks only two to three feet away from the sinks were completely free of obstructions. Unfortunately, many people don't realize this phenomena and brand the cast iron as a poorly performing product.

Cheap Labor & Cast Iron

Years ago, residential construction labor costs were insignificant. Time was not always an issue with respect to how long a particular task took to complete. For example, imagine how long it took to nail on those thin lath boards which allowed plaster to be applied to the walls and ceilings of houses. Think of the amount of time it took carpenters, using hand tools, to mortise hinges and locks into doors. The same is true for old style cast iron piping.

Old style cast iron piping was a chore to install. The plumbers had to pack oakum into each joint and then pour molten lead to seal the joint completely. This lead joint was then hammered to finish the job. The job of installing cast iron was tough, time consuming and dangerous.

Modern Methods

The cast iron pipe available today looks somewhat similar to old cast iron. However, the methods of installing the material have changed drastically. Gone are the oakum and molten lead. In their place you now find vulcanized rubber seals and stainless steel band clamps.

Cast iron piping systems can now be installed in a fraction of the time it took to install them 50 years ago. In fact, modern cast iron piping can be installed just as quickly as plastic PVC piping.



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Comments:

Welcome! I, Tim Carter, don't answer questions here. If you post a question here in the Comments Area, perhaps another visitor will help you. You need to go to the Ask Tim page if you want a question answered. Once there, look closely at how many weeks behind we are. Please be patient as you use this free service. If you have an emergency and need to talk to me, there is an option there for you.
Robert Thomas
21 May 2008, 11:26
I am trying to remove a piece of galvanized pipe from the cast iron pipe under the kitchen sink. This pipe is sealed into the cast iron and I cannot break the seal.The threads that the elbow connected to are damaged. I would like to saw of the damaged threads ,leave the rest of the pipe sealed in the cast iron pipe and see if I can install a piece of pvc pipe through the galvanized pipe. Is this a good alternative? If not what can you suggest. Thank you
susan
18 Oct 2008, 17:35
I would love someone to tell me how to take a 4" pvc pipe out of a cast iron 3" pipe.
Help.
Thank you,
Susan
Ron Charest
20 Apr 2009, 06:47
My wife and I bought a 1954-vintage home. While renovating the basement area, we discovered the horizontal run of cast iron drain piping has apparently corroded through in several places. Is there a way to seal this, or do we nee to rip it out and replace?
Jan Yeary
30 Apr 2009, 10:51
We are getting quotes on drilling a new well in SE Georgia. One contractor swears by galvanized pipe and the other by PVC. The price difference is over $2000 with PVC being cheaper. Both contractors have good reasons for using one or the other. What are the advantages of either? I don't want to go with the cheapest bid and be sorry down the road.
jeremy
08 Feb 2010, 21:13
the only advantage cast has over pvc is its noise reducing ualities it is very dense and thus does not transmitt sound well and makes for quiet pipes were pvc is not dense and transmitts sounds (ie the slooshing of water ging down the drain)like a radio tower. however cast is expensive hard to install or repair, not easily tied into on remodels/ relocation of facilities, did i mention expensive? and pvc schedule 40 is comparable in durability to cast (you cant park 80k lbs trucks on either without serious consiequences) but if installed properly both will grant you yrars of worry free service and pvc is much easier to wok with no matter the skill level of the home owner/handyman... just my thoughts if ou cant stand the possibility you might hear the drain through the wall go with cast oyherwise i like pvc.
jeremy
08 Feb 2010, 21:23
and as and after thought their are techniques for installing quieter pvc sewers such as insulating the points were it comes into contact with the structure ie studs, floor joists, their are also noise dampening mounts to fasten pipes to the structure i would suspect you coud wrap the whole thing in pipe insulation after the leak testing and that might help the noise...etc and i am sure their are options i am not aware of or remember at the moment do some research on the subject of quieting pvc pipes. good luck
José
09 Feb 2011, 13:57
You could say something about the PVC pipes. Not just the cast iron pipes.

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