We are currently renovating our bathroom ourselves on the 2nd floor. We were going to redo the tiles only, and we found a newspaper from 1947 around the old pipes which means it was installed a long time ago. We started to wonder if the pipes have to be replaced, but it’s not what we planned at the beginning.

One day we had to call a boiler technician, so we asked him if the bathroom pipe should be reinstalled. He strongly recommend to reinstall the entire bathroom pipes. He assumed the cost might be 10K to replace the entire pipes because it’s the 2nd floor, but he wasn’t a plumber. He told us to get a plumber for an accurate cost. I know it’s a good opportunity to replace them since we already opened the floor and the wall, but 10K is too much money for us.

As a non-professional, I think the pipes are in a good condition. They seem very sturdy and no leaking at all. I think they can stay 50 more years. I’m thinking about closing the floor without replacing the pipes. Please tell me if I’m an idiot.

bathroom floor with exposed plumbing

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    These old pipes are usually replaced because they start to fill with corrosion/rust and it affects the water flow. how is the water pressure/flow in this bathroom?
    – JACK
    Commented Nov 17, 2021 at 22:28
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    OTOH, that cast iron drain pipe is gold! It will be much quieter for water draining through it, so you won't hear toilet flushes and showers draining. You'll want to keep that
    – FreeMan
    Commented Nov 17, 2021 at 23:28
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    Not saying whether you should replace the pipes or not but if you're doing a DIY bathroom remodel then you should be able to do a DIY pipe replacement. Most of those pipes will be a standard length and if not a hardware store can cut and thread to the length you need. Time consuming but not difficult. As you install them periodically cap and test for leaks. Commented Nov 18, 2021 at 1:59
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    You could unscrew one short pipe and examine it. Then you would have all the information you need to make a decision. OTOH, you might cause a problem by futzing with it! Commented Nov 18, 2021 at 15:29
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    @SteveWellens If you try to unscrew a 74-year-old galvanized pipe, there's a decent chance you'll break it. Ask me how I know this. Commented Nov 18, 2021 at 16:31

6 Answers 6


You're not an idiot because you asked an intelligent question!

The problem with old iron/steel pipes is they rust on the inside which narrow downs the interior which results in reduced flow which gets worse over time and eventually they might even rust thru and cause a leak.

You've got it opened up, now is the time to upgrade. You'll hate yourself if you have to rip up a remodeled bathroom to replace 70 year old plumbing. PEX isn't hard to install and would make a great replacement and if you get the right tools (like a PEX expander), you can DIY, but if you're not comfortable with it, a decent plumber should be able to replace all that with PEX for a LOT LESS than $10K. I know pricing is off topic here, but just wanted to say.

The other advantage of PEX is even if it freezes, it is far less likely to burst like iron or copper would. DK where you are, but if in a cold climate area, that can be a plus.

EDIT NOTE: I updated my answer to include information provided by other comments and my further research. In a nutshell, PEX is far less likely to burst than copper or iron pipe, but it's still a possibility. Thanks for the other contributors comments.

  • @J..., having a long length of pipe where one section freezes is a significantly different situation than a small section of pipe where the whole things freezes. I also have to wonder what would happen if the same lengths of iron or copper were subjected to those same tests. My gut says they would be more likely to fail. Commented Nov 19, 2021 at 16:07
  • @J..., I can see how you can read it like that. I read that same sentence to say that PEX doesn't burst as easily as copper or iron. Commented Nov 19, 2021 at 16:16
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    Based on J... and computercarguy comments I did some research. According to what I found on many sites, PEX is far less likely to burst than copper or iron if frozen, but it is possible given extreme freezing. I'll edit my answer to include that. Thanks for the comments. Commented Nov 19, 2021 at 18:18
  • Steel water pipes may also interfere with your ability to insure your house, or your rates can go up once you disclose your house contains steel water pipe. Steel pipes can corrode and leak very slowly over time, leading to very expensive insurance claims. Not disclosing this may also cause problems down the road.
    – user101382
    Commented Nov 19, 2021 at 18:43
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    This! PEX is awesome, and a ridiculously easy DIY job. You'd be stupid to pay someone anything to do this if you're strapped for cash. All you need is a ~$40 crimp tool, dirt cheap crimp rings, a few ~$1 joiners (straight and right angle), and the actual PEX pipe (very reasonably priced but I forget the cost per foot). Commented Nov 19, 2021 at 22:04

Example images of damaged pipes: rusted and with calcium deposits

Top image is a pipe rusted through, bottom image is a pipe with calcium deposits

The lifespan of old galvanized pipes depends on water balance. If the water is alkaline over 7 pH the pipes will eventually close up with calcium deposits. If it is acid under 7 pH they will rust out and start leaking ( you may see rust at joints.) If the water is balanced this kind of pipe is expected to last 75 years. Hot water pipes generally deteriorate faster than cold pipes. 10k is more than I would expect to pay for this job, DIY would cost a few hundred $ at most for PEX. If there is no rust, and you have good pressure, I would expect to get another 8 to 30 years from these pipes. Weigh this against how long you expect the remodel to last.

  • 4
    Also, the rules of Stack Exchange require that you list the source of the images, even if it's "own picture".
    – FreeMan
    Commented Nov 18, 2021 at 13:18
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    I have no clue what you just wrote, I am a handyman not a coder. However, this seems to be a very informative site, I hope I can learn its arcane system, to be able to contribute to it. I did figure out how to get past the 5 minute error: select all, copy, cancel, edit paste, save, and it works! Commented Nov 18, 2021 at 16:14
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    @Danieljamar35 welcome to the site!
    – SQB
    Commented Nov 19, 2021 at 7:22
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    I was really glad that Danieljamar35 added those pictures — they're awesome! — and I'm sad that his reward was to get scolded for not labeling them properly, and to have his intelligence questioned for not immediately grokking a syntax which, let's be honest, is coder-friendly but layman-hostile. Commented Nov 19, 2021 at 15:50
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    @SteveSummit: not to mention that OP tried to do the very best thing: try to use a caption label. Replying that he should look for help (and not find anything because MD does not support captions) instead of readily helping is really not cool.
    – WoJ
    Commented Nov 19, 2021 at 16:30

The price the guy mentioned might be accurate for a whole house replacement including wall repair and painting. You only need to do what is under the tub and in the floor before it is covered back up. It should be replaced to the point where if any leaks do occur, it will not mean tearing up your new floor or anything in the bathroom. This will mean smaller repairs needed in other rooms if not accessible from the bathroom side to do a tie in. This will depend where the threaded ends are in walls or floor to set an adapter on to transition it to PEX or copper. There are 3 kinds of PEX, it is advised to stay away from "C". "A" and "B" PEX is the type to use, PEX A being the best.

Back at the tie ins. The most you would need I expect, and this is a guess that there would only need to be 2 to 4 holes in other areas at the worst to tie in the hot and cold in 2 different places. That is a hot and cold going into the bathroom, and a possible hot and cold going out to feed another area if it is set up that way.

Your biggest issue is the drain line. That will look like that picture on another answer since air gets in drain lines to allow rust to start. Water lines, perhaps not as much, but other deposits do form inside those types of pipe, calcium being the biggest offender of water pipes.


Must these old pipes be replaced?

No, unless your town has a code which states that galvanized plumbing must be replaced during an opportune time such as a remodel.

Should you? Yes. Don't wait for a must situation or else you'll be replacing a lot more than just pipes. Consider everything below your bathroom trashed.

My house was built in 1940 and 2 years ago I replaced all of the the downstairs galvanized water pipes with PEX; costed about $900. Once I'm ready to tear into the second floor you can bet your last dollar that I'll be replacing the galvanized pipes.

When removing the old galvanized pipe I was curious as to how difficult it is to unscrew these joints as opposed to using my sawzall so I grabbed some pipe wrenches and twisted a tee right off; the threads were left inside of the tee.

This particular joint would probably have failed in the next few years. It was rusted down to a pinhole about 1/8" in diameter and was the source of terrible hot water flow for our kitchen and upstairs bath.

Rust begins life on the inside of the pipe and if you start seeing surface rust that that means it has breached the entire wall of the pipe.

Make note of the water leak from the rust spot on the right.

Galvanized water pipe rusted from the inside-out and is leaking


  • So the zinc coating doesn't last very long? If it rusts like that, clearly the galvanization did not cover the iron against the water. Also, how long is PEX supposed to last, and is there any indication that the figure is accurate?
    – JDługosz
    Commented Nov 19, 2021 at 16:29
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    @JDługosz 80 years is unacceptable to you? Please define "very long"
    – MonkeyZeus
    Commented Nov 19, 2021 at 16:53
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    @JDługosz The longevity of the zinc coating is affected by multiple factors such as the thickness of the coating, frequency of water turbulence, and water chemical composition. Yes, once the zinc coating is gone then the pipe is quite exposed and will rust accordingly. This website has some good information: supremepipe.com/blog/difference-black-iron-galvanized-pipes. Overall PEX is much more desirable due to material cost, ease-of-install, and estimated longevity which is on par with galvanized steel and copper.
    – MonkeyZeus
    Commented Nov 19, 2021 at 17:09
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    @JDługosz In summary, 80 years is a respectable lifespan for metal pipe which transports water; entire houses can have shorter lifespans. If you had enough money to do all stainless steel then the plumbing would outlast several family generations. In fact, if the house were to be demolished then the metal would be saved and used in the next home.
    – MonkeyZeus
    Commented Nov 19, 2021 at 17:18
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    I don't recall making any claims about strength. I'm not a metallurgist so I cannot confirm nor deny your thoughts but I'm going to take a wild guess and say that the galvanization process wasn't invented just for fun.
    – MonkeyZeus
    Commented Nov 19, 2021 at 22:09

While galvanized pipes were originally expected to last 80-100 years, the quality of the water in your area can shorten the life of these pipes. Hard water with minerals breaks the galvanized coating from the inside and allows rust to start. If you can find a location to inspect the inside of a section, you can check the inside of the pipe for damage. Damage could also be mineral deposits that have effectively reduced the inside diameter of the pipe. If the pipes are clean on the inside, you probably have no real reason to replace them. IMHO.

  • 1
    With modern technology, inspecting the inside of a pipe no longer requires high-priced equipment and a large diameter pipe. You can fit a $5 camera on a long wire and peek inside the small pipe where you will connect the sink -- a joint you plan to open anyway.
    – JDługosz
    Commented Nov 19, 2021 at 16:32
  1. Metal tubes tend to have less biofilm than PEX tubing. Although it is not clear if PEX material does really increase the probability for legionnaires' and other diseases. Metal tends to block germs to some extend. Some users complain about a different water taste after installing non-metal tubing, but that could also happen after switching from non-metal to metal tubes (that happens much less frequently).

  2. The very robust inner coating with minerals, which is mentioned in other answers, protects the metal against direct contact with water. This contributes to a very long life expectancy. A cleaning with acids tends to increase the probability for pit corrosion - it should be avoided with old metal tubing.

  3. A "circuit breaker" for domestic water nets can be very helpful for a better sleep. It protects against big damage caused by water leakages or failing installations or Alzheimer's disease and opened faucets.

  4. The visible holes in the floor could be covered/filled in order to prevent insects or rodents to enter the floor/wall. A warm water line can attract animals.

  5. If there is enough space for tube insulation, it can save energy, reduce micro circulation and reduce noise.

  6. To prepare for a later substitution, PEX tubes could be installed under the floor without connection to the water net (no water stagnation if not yet used). Or bigger empty tubes with pull wires could be installed.

  7. Freezing water lines do crack most of the time if the freezing takes place in more than one place and 2 freezing zones are growing towards each other. In that case, PEX lines can also burst. If a line freezes from one side only, the pressure can be often released by the pressure relief valve next to a boiler. If the provider's line is not frozen, the pressure can be often released into the outside water net, since back flow preventers often do not work 100% reliable.

  8. Many problems in old metal installations are caused by the ignored golden rule: installation from less to more noble metal in flow direction. F.e., substituting a part of a steel tube with a copper tube resulting in the sequence steel - copper - steel will most likely cause (pit) corrosion in the downstream steel. Isolating plastic parts between the different metals will not prevent this type of (local) corrosion.

  9. If the boiler's sacrificing anode is consumed, small metal parts could also start pit corrosion, especially if hot water circulation lines are installed. If the current can be tested, it should be less than minus 0.3mA, measured against the boiler mass/housing. F.e., a value of minus 2mA is an indicator for a working anode, which does not need to be replaced.

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    What is "A "circuit breaker" for domestic water nets"? That's a term I'm not familiar with. Also, how does this answer the question of whether or not this plumbing should be replaced? It appears to me to simply be a list of facts.
    – FreeMan
    Commented Nov 18, 2021 at 15:24
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    @FreeMan "Water leak Detector with automatic water shut off valve" is the long terminus for that safety device. Most installers simply recommend an exchange of old tubes, but that is not always necessary. This sort of device costs about 400 Euros and is also useful in a brand new homes with brand new water tubing.
    – xeeka
    Commented Nov 18, 2021 at 19:51
  • Gotcha. It's a European term not necessarily familiar to those in the State. Thanks for the clarification.
    – FreeMan
    Commented Nov 18, 2021 at 21:10

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