Yep. Aluminum wiring can be safe, but you need to coat all the connections with anti-oxidizing grease. And even at at that, I don't know how long it lasts.
Copper pipe for water is often specified by code in commercial construction. I've heard this is due to lobbying by plumber's unions but not sure about that. Most residential construction will use CPVC or PEX these days.
I am a huge fan of PEX from a cost and longevity perspective (it can withstand some freezing of water without bursting), but copper is cool for its anti microbial and similar chemical resistance properties. If money was no object, I’d spec copper over plastics for water supply if I expected the structure to exist for 50-100 years. Disposable structures? Plastics all the way, dump the whole thing in a plasma gasifier upon retirement.
I’m less convinced. Copper is susceptible to its own failure modes. Water moving too fast in a copper pipe can erode the pipe, and “too fast” is quite slow, especially for hot water. If you want hot water quickly, you want the fastest practical speed, which means the smallest practical pipe, and you can easily run into the limitations of copper. PEX and CPVC tolerate considerable higher water velocity. (I think this is because copper’s passive layer can be scoured away, whereas plastic pipes don’t need a passive layer.)
If you have well water or water from anywhere other than a utility that controls the chemistry correctly, the water can dissolve your pipes. The rainwater from my roof makes copper instantly shiny, which is a bad sign for the copper.
That’s pretty uncommon, generally the joints fail before pipes do.
PEX with compression fittings is the closest thing to copper in terms of durability, but exists because of labor savings. Appropriately installed copper is the most durable interior water service and will comfortably outlast the life of the structure.
They say all it takes is not de-burring the pipe to create the turbulence.
We have a lot of problems in my county with copper pipes leaking. There are entire plumbing companies dedicated to finding the leaks and repairing them. There are still more companies dedicated to repiping.
I know of developments where they epoxy coated all the piping because they were getting so many leaks.
You can read about the huge class action lawsuits going on involving the local water utility (who is being blamed for water chemistry causing the issues. They point fingers elsewhere, obviously).
I’ve seen a copper pipe where in the middle of the pipe there is a pinhole leak on the top side of the pipe (too far for turbulence, can’t be cause by sediment).
If you want the most durable, I would think it would be either pex-a or perhaps 316 stainless steel (which is a valid code compliant option). But no one really knows, and it’s probably water chemistry dependent. It’s being argued in the courts now (for whatever that’s worth).
Stainless steel is awesome! Unfortunately the connections are not so easy. Stainless steel-to-brass threaded connections are probably safe under most circumstances but are dubious per the code. Push-to-connect fittings often use little stainless teeth to hold the tubing in, and this may work less well when the pipe is nearly as hard as the teeth. (John Guest makes special fittings for stainless steel tubing.) You can’t sweat stainless steel pipes.
Obviously everyone should plumb their houses with swagelok fittings! :)
Probably a better compromise is stainless press-style fittings. The tools are going to be much too expensive for the average homeowner plumbing needs, but they work out in the commercial sector or for professional plumbers.
MegaPress and ProPress are a couple of popular brands.
The also have an advantage that they avoid "hot work" in places where it leads to greater regulation / stringent safety precautions.
Washington Suburban Sanitary Commission (WSSC) changed its chemicals at some point in the late 1990s, and a lot of customers found pinhole leaks starting in their copper pipes. Considering the relative density of lawyers in suburban Maryland, I suppose there must have been a lot of litigation, though I don't remember hearing.
On the other hand, I lived in a rowhouse built during a brief window in which it was OK with the code to run PVC from the main into the house. Whatever PVC is good for, it doesn't handle shearing force well. Essentially all of the townhouses needed repairs (a copper "pigtail" through the wall).
Three pinhole failures in 30 yr old copper pipe in ten years in this house says otherwise. We've (hopefully) torn all that out - tired of replacing 1/4 of the house every time there's another pipe failure.
One possible contributing factor: flux must be removed from copper pipes (the inside!) for good performance. Plumbing codes require that flux meets ASTM B813, which means that the flux will flush out with cold water.
Sadly, even today, most plumbers will show up to a job site with petroleum-based flux that most certainly does not meet B813. It can stay in pipes for years, slowly leaching chemicals that do their job: weakening the protective oxide layer in the pipe. Also it tastes and smells terrible.
Not to mention water itself is horribly corrosive. Pure water will strip copper pipes. That’s the real reason fluoride was added to tap water:
1) it was cheap
2) it was safe to drink
3) it kept the water from eating the city’s pipes.
We had a city in Illinois do whole city RO and advertise the cleanest water in the country. Well it was the cleanest water going into the pipes, but if you own a house in that city the water coming out of your tap is full of old pipe!
Funnily enough, this is technically true, but would only manifest in a warped reality.
In the acidic/caustic scale, regular water is just slightly on the caustic side of neutral. (pH 5.5 or thereabouts?) - It won't strip the pipes it runs in. But that's not the kind of water we're talking about here. That would be pure distilled water.
It's the near-universal cleaning agent. Because of the complete lack of impurities, distilled water has the ability to absorb fair amounts of almost anything it gets in contact with. It also tastes really bad. (The taste of "nothing" for regular water is our calibrated baseline with various minerals and other impurities. If you take all of that out, the perceptual difference between expected and experienced is quite stark.)
For what it's worth, cavitation and turbulence are much more likely culprits to eat the plumbing material. Also: shoddy quality will always cause problems, regardless of your choice of materials.
Your statement is at odds with what I know about water.
Your saturation index is what drives water’s interaction with the surfaces it touches, not just pH. If the index is too high it will deposit what it’s carrying (scale) and if it is too low it will pick up material from the pipe it’s flowing through (corrosive).
1) That isn’t distinct from PH, it’s a refinement of it?
2) There is theory, and there is practice in the field. What you’re referring to is the equivalent of ‘wet bulb temperature’ for temps. Which is a thing, but water conditions for a given area rarely vary like temperature will - and are in control of the local water treatment plant. What you’re referring to was specifically made to measure and help control these conditions.
If copper piping is allowed by local code, they’ll know - and keep it within these ranges. Areas with water that is not easy to keep within these ranges will also corrode galvanized pipe (commonly used for water in most areas), and will likely also corrode brass fittings and valves (including back flow valves) commonly used in many areas, leaching lead, copper, etc. among other things. Those areas prohibit them by code for that reason.
Copper piping will generally not corrode unless PH is < 6.5 or > 8.5, which is significantly outside what most would consider reasonable water quality.
I personally have a well in an off grid location with 6.2 PH, and use only CPVC for that reason. Where I live, I’ve done some retrofits and replaced 75 year old copper pipe that was good as new inside.
> If copper piping is allowed by local code, they’ll know - and keep it within these ranges.
I think I’m misunderstanding you. Your original comment was “that’s bullshit” but this seems like it’s in rough agreement.
IIUC copper pipe will last for 50-100 years IFF you pass impure water through it. Pure water will eat the pipe. Same with galvanized steel and brass like you pointed out. So the city treated it with _something_ to keep the water from eating pipe (knowing copper pipe is code) and I’ve anecdotally heard that part of that “something” is fluoride.
From my understanding a negative LSI means the water will try to "pick up" atoms/molecules from the container it is in (corrosive). A positive LSI indicates it will lay down atoms/molecules (scale build-up).
A value of negative infinity tells me that pure water is going to eat the pipes.
That being said, I don't know if the LSI scale is well behaved as these values trend towards 0! The values of water purity in the equation seem to dominate both pH and temperature as those values trend towards 0 - no big difference in results if pH is 7 vs. pH is 3 and no big difference if water is frozen or boiling. Temperature can have a big impact for _very cold_ and _very hot_ but then you're dealing with solid water or steam and that doesn't really make sense to me for this model. That probably suggests the equation is only well behaved for a certain range for each value, and I'd suspect 0 is outside the range these equations can model for TDS, Calcium, and Alkalinity. But I can't find anything that defines the ranges the LSI model applies to.
And yet, distilled water tests a 7 with a PH strip, people use copper pipes with distilled water with no major ill effects, and distilled water won't eat it's way through a copper pot either.
You're clearly trolling someone. I guess I'm done wasting my time on you?
Your assertion is that 'pure water' will corrode copper pipe, so it needs to be 'impure' to not do so (using flouride of all things as an example?)
Yet, distilled water - which is as pure water as anyone will ever see outside a lab - doesn't do so to any meaningful extent. And you keep using various clearly inapplicable theory to try to prove a point that is clearly false in the real world.
This has nothing to do with steel wool, after all.
My understanding is that, if you take fluoride out of the water, you’ll need to replace it with something or the water will replace it itself (aka eat the pipe).
That obviously doesn’t mean fluoride was originally added for that reason though.
I doubt most freshwater sources have enough minerals in them to not be corrosive enough to need to add anything to reduce corrosiveness (ground water wells, rivers, etc...). The only purpose for adding fluoride would be to add fluoride for dental purposes.
The only thing I could think of that might have corrosive issues would be desalination water that was overly purified like the sibling comment mentioned. But even then, they should be adding some kind of minerals back before distributing it to people's homes. Ultrapure water tastes horrible and likely isn't safe for drinking long term.
> Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something.
I’m totally open to being wrong. I’m eager to learn - which is generally why I share information. If I don’t readily share what I know to be true, like in this case, nobody will ever correct me and I’ll spend the rest of my life being incorrect.
On HN you generally start by telling someone why they’re wrong and supporting that in some way.
I.E. if you know/believe fluoride was added for another reason - that’s a good place to start.
Or if you know/believe purified water is not corrosive, that would be a good place to start.
Compression fitting will last longer than copper. If a copper fitting is done wrong it can pit. I'm going to be honest here and tell you I can't find sources for this but I thought I've seen it before in research -
Copper lasts 50-60 years. I believe that's type L which is used in the wall in homes in the US. The skill required to create a high quality copper joint takes time and a person may still make mistakes. A PEX compression fitting is basically just closing a tool. The probability of mistakes is lower.
I'm not familiar with the possibility of contamination in pex, is this due to the material?
I am fairly sure type M is used in normal residential construction. L is heavier and use for more underground or commercial applications. You can quickly tell the difference because M has red writing on it, while L have blue.
The problem is there are no "L" fittings and the normal fittings used for L copper can be quite poor. For this reason and others, some people like ProPress fittings which are very high quality (and expensive).
I'm curious why you would choose copper over PEX. It seems like PEX is really the best choice available these days in terms of near infinite lifespan, easy to work with, and affordable.
> It’s tough to beat copper pipes for longevity, which on average last 50 to 70 years, compared to PEX, which has an expected lifespan of 30 to 50 years. PEX’s life expectancy can be shortened by the use of extremely hot household water (180 degrees Fahrenheit or higher) or if the water in the home contains high levels of chlorine.
> Copper’s life can be shortened by highly acidic water. When installed under typical conditions (i.e., your home is connected to a municipal water system), copper can be expected to outlast PEX by about 20 years. If you’re on a private well, have your water tested prior to retrofitting your water supply system. Local County Extension Offices can test well water to determine whether it’s high in acid or chlorine.
I’m a buy it for life sort of person, and will pay a premium for longevity. Future myself or others will thank me (buying or building something that will outlive me? Plant trees whose shade I’ll never sit in and all that jazz)
Well now you've sent me down a whole other rabbit hole wondering about who these people are who keep their hot water at 180 degrees or about how much chlorine constitutes high levels.
Yep, if you ever see bluish rings in your toilets, and you have copper piping, check your water pH, that might be part of your home's plumbing that's now ringing the porcelain.
I think to be truly fair Option A has to consider the energy generation you will have to do elsewhere to make up the difference, which may or may not be carbon neutral - or to flip it, the energy generation you won't have to do due to Option B. So it really depends on the energy generation landscape you are within.
> [PEX] can withstand some freezing of water without bursting
I learned that the hard way last year. Had PEX water lines hard freeze during the crazy February weather in Texas area last year. Thankfully no burst pipes!
There are also a new aluminum alloys (aa-8000) with better mechanical properties. The biggest issue is that that the trades/DIYers need to learn new processes. Treating aluminum wiring like copper wiring is a disaster. Also need to overcome the stigma from the aluminum experiment 50 years ago.
It makes a ton of sense to switch to aluminum in housing though. For the same current capability the wire is significantly cheaper, lighter, and stronger.
Aluminum also has issues with heat expansion and contraction causing connections to loosen faster.
With properly rated connectors, not a problem, but not all are, and not everyone knows it's a thing.
Copper pipe is much more durable as long as the local water isn't acidic, which is rare. CPVC has had a number of issues over the years (including leaching of chemicals and brittleness over time), and PEX is still relatively unproven. It's predecessor product had huge insurance claims due to failing connections after 10+ years.
Pex gets eaten through by rats and then you get to replace 20% of your house if you don't catch it in time. Copper for water is better, or you could run PEX in CSST conduit everywhere (never seen or heard of it). I don't know enough about rats and CPVC, but it seems a bit safer at least. But you will get rats, it's just a question of when.
Why doesn't anyone run PEX in CSST conduit (flexible galvanized steel, for those who don't know, as is commonly used to protect wiring) if this is such a problem? Flexible conduit is a hell of a lot cheaper than copper pipe, easier to bend and connect too.
It looks good as well. At the same time, all these plastic materials are petroleum based products we are piping our drinking water through, although we likely have no choice for this century at least.
Just read an article in a local paper about banning gas connections in new housing. Had a direct quote from the union saying they aren't inherently opposed per se, but need ___ $$ to offset any job losses.
And then next graph mentioned that union was part of a lobbying pac thing fighting for the status quo
> but you need to coat all the connections with anti-oxidizing grease
Actually, no you don't. Only wires from like 30 years ago need that. Modern aluminum wires do NOT need the coating. In fact in some places you will fail inspection if you add the coating.
Most people have not updated their knowledge on this, since they don't work in the industry.
Copper pipe for water is often specified by code in commercial construction. I've heard this is due to lobbying by plumber's unions but not sure about that. Most residential construction will use CPVC or PEX these days.