Is stainless steel water piping more durable than copper?

Question

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?

Answer 1

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.

Answer 2

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.

Answer 3

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.

Answer 4

If stainless steel is actually an option, I'd always go with stainless, as it has significantly less corrosion than all other options. Specifically 316 stainless, which can withstand chloride levels present in marine conditions. 304 stainless will be strong in very typical levels of chlorides, but if you are experiencing extremely accelerated corrosion, I strongly suspect high levels of chlorides.

The only concern with using 304/316 stainless is galvanic corrosion, meaning the stainless steel must never touch most other metals. If it does, because the stainless is so resistant, it will end up accelerating corrosion on the metal it was touching. Basically turning that metal in to a sacrificial cathode. So make sure your fittings are cleared by the manufacture, for connecting stainless to something else.

Others mentioned PEX, I would NOT use anything other than 316 stainless in a high chloride environment, as chlorides will attack all other materials. This is especially true when heat is added to mix, such as water from the hot water tank, it dramatically accelerates the corrosion effect of the chlorides.

Galvanized steel should never be used for pipes, even though it was used historically, and can even be found today in older homes. The galvanized coating just doesn't provide nearly enough corrosion resistance, even without the present of chlorides, and the pipe will even corrode from inside. The zinc coating acts as a sacrificial cathode, and only in dry environments could you expect it to last a typical pipe lifetime.

Answer 5

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.