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Old 11-04-2012, 10:43 AM   #1
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Original (?) galvanized water supply pipes replace with PEX, CPVC, copper?


I have a 1940's house that is plumbed with a mixture of galvanized and copper supply pipes. I haven't experienced any leaks from the galvanized pipe, nor do they seem to be filling up (water pressure is great). About one-third to one-half of the system is copper right now. There are areas where the trunk is galvanized and the branches are copper and vice-versa.

Currently, I'm moving my laundry appliances and laundry sink a few feet in the basement (this will require some minor re-plumbing of supply pipes). I plan to replace the basement drop ceiling with drywall in the near future. These projects raise the questions of whether to replace all the galvanized pipes and, if so, with what.

This is a one-story house, so I have fairly easy access to nearly all the plumbing above the drop ceiling. That will obviously change quite a bit when I drywall the basement ceiling.

There are a two spots (that I have found) where pipes appear to be corroding: at the outlet of the water heater (copper) and in a hot water supply to a sink (copper -> galvanized transition). Pics are attached. Perhaps these are the result of a dissimilar metals issue?

My questions are thus:
  1. How badly do I need to replace the galvanized pipe?
  2. If the galvanized pipe is a serious problem, what do I replace it with? I have no experience plumbing supply pipes.
  3. If the galvanized pipe replacement is not necessary, how do I deal with these two corrosion issues? The two spots I have noted will remain accessible (I won't be drywalling those areas).
Attached Thumbnails
Original (?) galvanized water supply pipes  replace with PEX, CPVC, copper?-water_heater_outlet.jpg   Original (?) galvanized water supply pipes  replace with PEX, CPVC, copper?-sink_supply.jpg  


Last edited by TomServo; 11-04-2012 at 10:47 AM.
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Old 11-04-2012, 10:53 AM   #2
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Original (?) galvanized water supply pipes replace with PEX, CPVC, copper?


Galvanized pipe is well known for corrosion issues, you have actually gotten very long life out of the pipes. Some people prefer the "run to failure" approach, which means basically waiting until there is a failure, then replacing just the failed section. Some people run to failure, then replace all the galvanized pipe at once. Some people prefer to proactively replace the galvanized pipe before it fails.

My house is on well water, and had copper pipe. My well water is pretty acidic, and after about 50 years the copper pipe began to develop pinhole leaks. I replaced pipes as they began to leak for a couple of years, and eventually decided to replace all the piping in the house with PEX. You will find numerous threads on this forum discussing the relative merits of copper, PEX, PVC, CPVC. Each one has their fervent supporters and detractors. I don't think you will find anyone on this forum who is an ardent supporter of galvanized pipe for potable water, or lead pipe for water. If you have a few hours of spare time, do a search on PEX or copper pipe, lots of comments.

As for the dissimilar metal issue, you will always get a reaction of you connect copper to galvanized directly. The simplest way to avoid the reaction is to install a dielectric union at the joint. I recommend this approach, there are other techniques, but unions are proven technology, easy to install, and relatively inexpensive. Unfortunately it is a little late to fix the problem if corrosion has already occurred, in that case you need to replace the damaged pieces and install a dielectric union as part of the installation. Unfortunately it is easy to damage the threads in a water heater from corrosion, so be very careful when removing a corroded galvanized fitting from the water heater, and be prepared to clean the old threads before installing a new nipple.

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Old 11-04-2012, 11:13 AM   #3
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Original (?) galvanized water supply pipes replace with PEX, CPVC, copper?


Thanks for your response. Yes, I have read a bit about copper vs. PEX vs. CPVC. I wonder if, because part of my system is currently copper, it makes sense to simply replace the remaining galvanized pipes with copper. Perhaps there's no advantage to an all-copper system compared to a mixture of copper and PEX, for example. Copper seems a bit less DIY-friendly as compared to PEX, from what I've read.

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Unfortunately it is easy to damage the threads in a water heater from corrosion, so be very careful when removing a corroded galvanized fitting from the water heater, and be prepared to clean the old threads before installing a new nipple.
The fitting on the water heater outlet is actually copper. I assume the solution is the same, though, is it not?
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Old 11-05-2012, 12:21 PM   #4
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Original (?) galvanized water supply pipes replace with PEX, CPVC, copper?


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The fitting on the water heater outlet is actually copper. I assume the solution is the same, though, is it not?
Could anyone weigh in on this issue? I'm wondering what to do to address the problem with copper fitting on the water heater pictured above.

Also, in reading about the problems with galvanized pipe, it appears that "pinhole leaks" are an indicator of degradation. I see none of those in my plumbing. Is the lack of such problems a sign that things are in better shape than the age would suggest? I really don't want to replace these pipes if it's not necessary.
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Old 11-05-2012, 12:51 PM   #5
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Original (?) galvanized water supply pipes replace with PEX, CPVC, copper?


You should install dialectic unions on the heater for two reasons. It will curb the corrosion and make your heater easier to replace in the future( unions are required in my area)
The bigger problem with galv. Pipe is interior corrosion and mineral/sediment build up- usually not visual until you cut the pipe open. Copper is more likely to develop pin hole leaks.

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Old 11-06-2012, 11:07 PM   #6
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Original (?) galvanized water supply pipes replace with PEX, CPVC, copper?


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Originally Posted by TomServo View Post
Also, in reading about the problems with galvanized pipe, it appears that "pinhole leaks" are an indicator of degradation. I see none of those in my plumbing. Is the lack of such problems a sign that things are in better shape than the age would suggest? I really don't want to replace these pipes if it's not necessary.
If you're planning on doing some work anyways, replace a run of the galvanized pipe and see what it looks like inside. Pinhole leaks aren't the only indicator of problems with galvanized pipe, they get barnacles inside that cut the flow down a ton. I've pulled quite a few 1" galvanized pipes out of the ground that have about a pencil diameter left for flow inside.


(This isn't actually it, just an example I pulled off of google).

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