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After thirty years of usage, the plumbing in my house is starting to fail progressively. The water pipes in my house is made of copper, one of which is suffering from pitting, which results in a pin-hole leakage. I tried to repair with plumber's putty, but that did not work as the water cannot be drained out completely even when the mains is shut. I have also tried taping and clamping, but it wouldn't work either.

As a portion of the pipes running through my house is buried underground, there could be leakage undetected elsewhere. My intention is to replace the entire network of water pipes with one that is exposed and easier to inspect and maintain. I am given two options, copper or stainless steel. The stainless steel option is currently 20% cheaper, but I am not sure whether this is the better option in the long run.

Is stainless steel piping more durable than copper?

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    Plumbers putty, and tape are not designed to repair leaks in pipes. – Tester101 Oct 10 '14 at 16:13
  • In general yes, but your copper pipes seem to be failing abnormally early, possibly due to installation defects, or substandard quality copper. In most cases, the pipes will outlast the rest of the building. – gbronner Jan 11 '16 at 15:39
  • What is the water supply? Have you had any testing done on it? If it's a private supply, what type of treatment do you have on it? Curious that only 'one' pipe is having this issue. Is there something specific to that room that could be corroding the pipe? – gregmac Jan 11 '16 at 15:42
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    People pipe in SS? Never seen it. We're talking about galvanized, right? – Mazura Jan 11 '16 at 15:49
  • If your copper pipes are wearing this quickly, check the anode in your water heater. The anode is there to sacrifice itself instead of your pipes. diy.stackexchange.com/questions/21984/… – Keeta - reinstate Monica Mar 22 '16 at 11:53
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In general, yes, stainless steel is more corrosion resistant than copper. It forms a tightly bonded oxide coating which tends to prevent further corrosion.

If replumbing a house where copper pipes corroded (this is more prone to happen in some areas than others due to water chemistry differences) my first instinct at this point would be to use PEX plastic tubing, but for metallic piping I would choose stainless steel over copper even if the price was the same.

If on a water supply that is treated with chlorine, or which has salts, there is a slight possibility of a stainless-steel specific problem (chloride corrosion). Certain grades of stainless (316, 316L) are more resistant to this form of corrosion than other grades of stainless, so precisely which stainless piping you are being offered will matter.

Still, I'd choose PEX by preference - should cost less, and it's not going to corrode.

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Depending on which type, Stainless is the better option: Corrosion resistant, strong, durable and can withstand temperatures colder and hotter than you'll likely need and won't leach harmful chemicals or minerals / metals into your water supply. The disadvantages are the pipe is hard to cut or bend and could crack or burst if the water freezes in the pipes but, this can be avoided if you drain the plumbing in cold weather if you won't be using them or heavily insulate them.

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316 stainless. No question. But do you have any idea what it runs? It's not cheap. If your worried about corrosion or longevity, think of high end scientific instruments, processing and factories, power plants, medical and other similar applications. It's at home in all of those apps, but totally overkill for a home.

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I think it is clear that stainless steel has a longer shelf life than copper - or at least the copper available to most for residential plumbing.

However I think there are two really significant issues with stainless steel that would cause me to never use it for my own house:

  • stainless steel is galvanized and that will probably produce lead to the water supply. Even in trace amounts, I will pass.

  • stainless steel is just a bitch to deal with. For someone that isn't well versed in stainless steel I would allow for 3-4 times the install time compared to PEX.

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    Can you clarify? My understanding is galvanized steel and stainless steel are two different products. I've never heard of 'galvanized stainless steel' – DA01 Jan 11 '16 at 16:29
  • Agreed, see my comment on the question. I think we need an answer here that talks about dielectric fittings... That's my only reasonable explanation for why a copper pipe wouldn't outlast your house. – Mazura Jan 11 '16 at 16:38
  • @DA01 - Maybe I am oversimplifying the term galvanization but depending on your grade of stainless steel it will require trace amounts of lead to provide a exterior coating. I have never seen stainless steel sold as "lead free" by me - however I am in the midwest and we are 20 years behind on things like this. – DMoore Jan 11 '16 at 17:07
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    This is complete fabrication - A: Galvanizing is zinc. B: lead is not required for stainless to provide a coating. The coating on Stainless Steel is formed by oxidation, primarily of chromium. Looking up 316 and 316L, Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Molybdenum Nitrogen Iron are listed - no lead. Lead is commonly used in brass to make it more machinable - it is not a component of either 304 or 316 (with or without an L suffix) stainless steels, which are the most common types of stainless steel. – Ecnerwal Oct 26 '16 at 21:59

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