Copper is one of the best known conductors of heat. Wouldn’t this waste energy by dumping heat from the water into whatever the pipes are touching? Also, with metal prices the way they are, I doubt copper saves any money.
I am by no means an expert, but it seems to me that you will only find copper pipes in older construction. New construction will almost always use PVC or similar materials for plumbing. Before the invention of these plastics, copper probably was the cheapest alternative. Compared to the alternatives (iron, IDK what else), copper was the probably the best choice both for price and work-ability.
Hot water pipes would also commonly be insulated, so presumably they were aware of the heat transfer problem, it was just the best they could do.
It doesn’t rust.
Copper’s malleable and light so it’s very easy for plumbers to manipulate while working and it has as tendency to inhibit the growth of bacteria and slime so if you go away for a week and leave water in your pipes, you are less likely to get sick. They also generally don’t leach anything into the water.
But a lot of places are using PVC because as you pointed out, copper’s expensive.
Copper is soft, bendable, durable, relatively inert, and very easy to join with solder. Before copper plumbing, lead was dominantly used for supply. (Plumber is from the Latin plumbum = Pb = lead.) Lead is also a relatively good material for constructing plumbing systems, but there’s the small matter of its toxicity. And it tends to crack and buckle easier than copper pipes. Hot water copper pipes can be easily insulated by wrapping them with pipe insulation.
Cast iron is generally only used for drainage and venting.
These days, everybody is crazy about PEX for supply of both potable and heating water. It’s cheaper, lasts forever, is completely inert, and you can roll it out in whatever length you need (no fittings.) PVC has replaced cast iron for drain-waste-vent systems.
But there’s still plenty of people using copper for old work and other applications. It’s not going anywhere. And metal prices have taken a pretty severe beating in the last year or two.
Copper is antimicrobial.
For certain values of “older”. My house was built in 2004, and it’s all copper piping.
In most new construction, plumbers have moved to using PEX over copper.
ETA: My house was built in 2006 and is all PEX.
What are the downsides of PEX? I see it touted on many home improvement shows but then there’s always the local plumbers who poo-poo the stuff. But I don’t know why.
PEX requires specialized tools. You also don’t want to leave it exposed to sunlight. Other than that I can’t think of any big downsides to it.
When I bought my house, I went thru and put insulation tubes around the entire hot water supply (except for some short runs in walls to sinks).
In one or two places, the pipes touched cold water pipes where they crossed. Someone got lazy. I was able to wiggle the insulation between such spots.
Generally, the only thing touching the runs of the pipes are the wire hangars holding them near/against the studs. The wires barely have any mass and the studs are good insulators.
I think a significant source of loss is at the fixture end. The cold and hot pipes hook into a bigger piece of metal at several (but not all) of them. You’d almost have the same situation with plastic pipe except the only conduction is via the water alone, not the pipe and the water.
You have copper installed because it’s going to last with few worries. The history of plastic piping is littered with the Next Big Wonder Crap that people eventually discover aren’t so wonderful. Good stuff generally costs more.
True for polybutyline, which was a disaster, but PEX has been around since the 1960s and has become more and more accepted every year. It has an excellent track record and is a mature technology.
Copper is certainly still around. I would be very curious to know why the builder chose to use copper when PVC and even PEX were widely available by then. It surely must have been the most expensive option, without any substantial advantage that I can see.
I can see a situation where the plumbing contractor was an older fellow who was just more comfortable working with copper, or even a somewhat unscrupulous contractor who realized he could mark up an estimate for copper pipe more so than for plastic, especially if he made much of the supposed benefits.
I know from personal experience that there are plenty of people out there that will pride themselves on paying extra to get “the very best”, even if the benefits are marginal or even imaginary.
There’s one advantage with metal pipes: if the pipe freezes, it’s pretty damn easy to unfreeze it by hooking it up to a welding power supply and running current through it.
So, here’s an ignorance-fighting question for those in the know. An average homeowner (me) does not ever see the pipes, so I cannot know what they are made-of. I guess I thought they were plastic, but maybe they are all copper, both cold and hot water(?). The only water pipes visible are at the water heater, and the input and output are copper. Should I assume all water pipes (water supply, not waste water) is all copper? Are the waste water pipes also copper? Thx
Waste water pipes are going to be ABS, PVC, or Iron (if you have a really old house).
If the pipes going to your water heater are copper, it’s a good bet the rest of the pipes are copper, too.
No, hardly ever.
Drain, waste, vent plumbing is either clay/ceramic (very old), cast iron (old), galvanized (also old), black plastic ABS or white plastic PVC (current).
It’s common for DWV plumbing to be combinations of these, both because it’s been added to over the years, and different types can be used in different parts of the house.
What IS an old, less desirable option is galvanized … I had mine replaced with copper in the 90s. Copper repipes were a common thing at that time, to replace old 50s galvanized. Copper was probably cheaper then, though.
I just recently had a new water heater installed. The plumber told me that the pipes going into the heater (both hot and cold) were some sort of steel (sorry, I don’t remember that adjective before “steel”). He said that “the code” required copper. So he removed about six inches from the ends of the pipes and replaced them with copper. No, he did not charge extra.
Can anyone explain why six inches of copper pipe going into the heater makes a difference?