I am living in an old building where the old galvanized steel pipes are still in use indoors.

Rather than upgrading to copper pipes, can I reuse these galvanized steel pipes for hot water (from a gas heater for showering)?

I have the impression that galvanized steel pipes are very vulnerable to corrosion when used with hot water. But I don't want to change to copper pipes because some of the galvanized steel pipes are conveniently available next to my gas heater hot water outlet.

  • 3
    You'll have to inspect the pipes first, often this is what old galvanized pipes look like inside.
    – Tester101
    Apr 27, 2012 at 11:43
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    I'm having a hard time finding good citations, but: it is thought that hot water affects the galvanized coating and increases the rate of corrosion and build-up inside the pipe. Galvanized pipe is apparently no longer allowed by code in Canada for (treated?) potable water (inside, anyway). Depending on the chemical composition of your water (pH, dissolved minerals) it may react with the pipe, causing other contaminants (a concern mostly if you are not on city water). Though you don't typically drink shower water, it does get absorbed into your skin and dispersed into the air (and your lungs).
    – gregmac
    Apr 27, 2012 at 21:40
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    @gregmac This link agrees with your comment on increased corrosion and build up in the pipe, also as a side point it mentions the problem connection copper to gal eg new hot water pipe to old.
    – UNECS
    Apr 28, 2012 at 6:22
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    We're using city water in our properties and every one that has galvanized pipes are just as corroded and gummed up as the picture posted by Tester. Apr 28, 2012 at 14:11
  • 1
    Have you considered using PEX? A lot less work than switching to copper.
    – DA01
    May 28, 2012 at 17:54

2 Answers 2


If you have the opportunity to replace your galvanized pipes, do so. It's an inconvenient project, involving opening up a lot of walls, but as you can tell from the comments, galvanized pipe is problematic at best over the long term.

It will frequently develop (as is the case in my own home and in my rentals) pin hole leaks. The only good news with galvanized on that front is - the gumming will often re-seal those pinhole leaks, but not all the time, as my basement ceiling could have attested, before I gutted the whole thing.


Some plumbers and the posts above suggest replacing galvanized pipes should almost always be done. In my case, I believe that SOME of the replacement was a mistake.

I replaced my galvanized steel pipes with PEX pipes. The old house I live in had galvanized drain pipes which were badly deteriorated. The entire drainage system required replacement.

The plumber indicated that it was just a matter of time before the other plumbing (also galvanized) failed. I accepted his suggestion to replace all plumbing.

When the water pipes were cut out, I found there was very little corrosion, even though the piping is over 50 years old. The one exception was the pipes from the valve to the shower head, which only had a ¼ inch hole (still adequate water pressure).

Wikipedia indicates the useful life for galvanized pipes is 50-70 years, copper is probably good for 70, too. PEX (rubber with cross fibers) are warranted for 25 years and probably good for 50 (Wikipedia), provided a rodent doesn’t chew them in two.

I concluded the issue relates to oxidation. The drain pipes corrode quicker because there is air in them. The water pipes have little oxygen because there is always water inside (an exception: from the valve to the shower head, where there is air).

Pipe corrosion has NO adverse health effects provided you have clean water (well systems can have minerals/lead).

Plumbers at supply stores told me they recommend replacement of: (1) drain pipes and (2) use PEX or copper piping from the main water lines to existing outlets.

There is an argument to be made to do everything at once (all materials at the site; maybe you can sell the house for more with “new” plumbing). But my pipes had a lot of wear left (only 5%-20% corrosion). I probably spent an extra $1,200-$1,500 that could have been delayed decades.

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