Updated September 11, 2023
Copper plumbing is ubiquitous in North American homes, and has been for decades. There’s no surprise, then, that questions about copper pipes are also quite common. Read on to learn all you need to know about residential copper plumbing.
Copper is an elemental metal, easily workable, with high thermal and electrical conductivity. Humans have used it for as long as 10,000 years. This versatile metal is used for everything from wires to cookware to roofs to jewellery, and of course: plumbing. Copper plumbing is an ancient invention, dating back as far as 5,000 years to the earliest kingdoms of ancient Egypt.
Modern copper plumbing, the type most of us have in our homes, started becoming common around the 1930’s. It’s fairly easy to install, tends to last a long time, and can be used for both hot and cold water; it’s no wonder that copper pipes are so popular. Copper plumbing was also fairly inexpensive until recently, but the price of copper has increased sharply since the early 2000’s.
In North America, copper pipes are standardized. There are four common types of copper pipe used for plumbing. The different types are differentiated by the relative thickness of the pipe walls. You can buy each type in multiple sizes, but the relative thickness will be standard.
Type L and type M are the two most homeowners will be concerned with. A common misconception – due to the aforementioned red and blue printing – is that type L is for cold water and type M is for hot water. That isn’t the case; the types refer only to different thicknesses of pipe wall. Types L and M are both acceptable for residential plumbing systems, but some local building codes may specify that only type L be used. Type M is much cheaper, but may not last as long due to the thinner walls, so consider the trade-off carefully if you’re installing new plumbing.
There’s one other way to categorize copper pipes: soft vs. rigid.
Soft copper piping is easily bent, which makes it very easy to install in tight or crowded spaces. It’s more expensive than rigid pipe, so isn’t commonly used in home plumbing systems, except perhaps in spots where the added flexibility is necessary. Soft copper tubing may also be referred to as annealed temper, a reference to the metallurgic process it undergoes to make it pliable. Not every size of pipe is available in soft form.
Rigid copper pipes are the most common. They come in long, straight sections, and are more difficult to bend by hand. They often need elbow fittings in order to turn sharp corners. Rigid pipes are cheaper than their softer counterparts. They are also referred to as drawn temper.
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Copper plumbing is usually installed in long, straight sections. The pipes can be cut or bent to fit where they need to fit. Individual lengths are joined together by soldering the ends into fittings, which couple them to the next length of pipe. The pipes run inside walls or underneath floors, carrying both hot and cold water throughout the dwelling. There will be one set of copper pipes for hot water, and a different set carrying cold.
Copper plumbing can normally be expected to last 50 to 70 years. That can vary quite widely, however, depending on local factors; water pressure, water acidity, and humidity are just three examples of factors that affect the lifespan of copper pipes. Acidic water could have pipes beginning to sprout pinhole leaks in a few short years. Individual joints and fittings may fail and begin to leak sooner than the rest of the plumbing system. It’s not unheard of for copper plumbing in favourable conditions to last even longer than 70 years.
Copper plumbing is nice because it’s fairly low maintenance. As long as it’s properly installed and isn’t being overstressed by acidic water or high pressures, you won’t have to worry too much about upkeep. That being said, no system is ever perfect. There are a few things you can do to keep your copper pipes operating smoothly for years to come.
Corrosion in copper plumbing systems comes in many forms. Unfortunately, it often happens inside the pipe, in which case you might not notice it until the damage is already done. Discoloured or sulfur-smelling water coming from your taps can be a sign of corrosion, but there may be no outward signs at all. You can, however, monitor signs of outward corrosion any place in your home that the plumbing is exposed, like near the hot water tank. Catching corrosion early allows you to take steps to prevent it getting worse.
“If you see blue-green or white corrosion on the pipe, there are two things for prevention you can do,” says contractor Morris VanAndel of Vanwest Developments Ltd. “If you’re on a well system, and you see corrosion, get your water tested to see if the pH of the water is acidic or basic. If that’s the case, you can look into neutralizing it.”
VanAndel recommends that people on well systems get their water tested annually regardless of any corrosion problems. The Government of Canada suggests a general test at least every two years (or any time you notice a change in the water’s taste, smell, or colour) and a bacterial test every six months. If your home is connected to a city water supply, the municipal water utility should be taking care of this part for you.
The other preventative measure VanAndel recommends is checking to see if the corroding copper is in contact with other metals.
“What you have to look for is any metal touching the pipe, because that starts the process of electrolysis,” he says. “It can be a nail, a metal strap, or in a lot of cases, galvanized duct work.”
This electrolysis occurs in plumbing when two dissimilar metals are in contact with each other in the presence of an electrolyte, in this case water.
“Pipes can be supported by wood, plastic clips, or copper clips without a problem,” VanAndel continues. “But if there’s any kind of other metal strapping that the pipes are being supported with, simply replacing it can stop the corrosion process.”
If you’ve checked your water and you’ve checked for metal contact points, but you still can’t figure out your corrosion problem, the issues may be the result of faulty installation. VanAndel says that copper corrosion can be caused by pipe joints that weren’t de-burred properly when they were installed. It could also be the result of incorrect use of flux when the joints were soldered together. In either case, removing the affected sections and installing new pipes – correctly – may solve the issue.
When still water rests inside a copper pipe for a period of weeks, it will begin to eat away at the copper. New plumbing systems should be designed by professionals, who will know how to maximize water flow. If you’re going to be leaving your home unoccupied for an extended period of time, you’ll want to drain your water system (and inform your home insurer!). This has the added bonus of protecting the pipes from freezing damage, which copper plumbing is particularly susceptible to.
On the flip-side, when the velocity of water in your plumbing is too high, it will be susceptible to erosion corrosion. Again, this is part of having your plumbing system designed by a pro; they’ll know to use the right sizes of pipe in the right places to avoid this problem. If you ever replace sections of your plumbing, make sure you use the same size of pipe as the one being replaced.
If your corrosion prevention is on point, there isn’t a lot more that you’ll need to worry about. If your copper pipes are routinely exposed to moisture, they may begin to stain on the outside. If you have exposed copper pipes, you may wish to remove this staining. The most effective way to clean the outside of copper pipes is with a calcium/lime/rust cleaner, diluted 50% with water. Make sure you use the proper protective equipment, including a facemask and gloves. Dip a cotton rag into your diluted cleaning solution, and use it to scrub the pipe clean. Using a soft material like cotton will help you avoid scratching the pipe surface. Once the pipe is clean, wipe it dry with a different rag.
The most common problem you’re likely to encounter with a copper plumbing system is pinhole leaks, caused by corrosion on the inside of the pipe. Since most plumbing is hiding behind walls and ceilings, you’ll probably notice wetness seeping through drywall or ceiling tile before you see the actual leak. If you see wet spots forming, the first thing to do is shut off the water. With that done, you’ll likely have no choice but to cut into the ceiling to locate the leaky pipe. It’s unfortunate, but once it’s gotten waterlogged, the ceiling is ruined anyway.
Depending on the leak, it may be identifiable by a spot of green staining on the pipe. If you can’t locate it this way, you may have to turn the water back on to see where it’s coming out.
Once you’ve located the spot, the next step is to fix it. If the leak is small, and affects less than half an inch of the pipe, it will be possible to repair by cutting away the damaged section and installing a pipe coupler. Larger sections of damage may require that you replace a whole section of the pipe. If you’re comfortable with soldering, you can do the repair yourself. Otherwise, contact a licensed plumber to do it for you.
Your home insurer will want to know what type of plumbing you have in your home, and when it was installed. They’ll want to know if there have been any issues with water leakage in the past as well. If your home has copper plumbing that’s still in good working order, your home insurance provider should have no issues with it. If you’ve had problems with leakage in the past, they may ask you to replace the system with a new one before they can issue a policy.
Leaching refers to the process by which trace amounts of copper are picked up by the water flowing through the plumbing system. This can happen if the water is slightly corrosive, which is common in homes that get their water from a well. Small amounts of copper in the water are not harmful, and in fact copper is a micronutrient essential for all living things. Small amounts of copper are common in all water, but elevated amounts can cause health problems. The most obvious sign that your pipes may be leaching copper into your water is the presence of blue or green stains on your taps, showers, toilets, etc. At low levels of copper, water can cause staining and still be safe to drink. If your water tastes metallic or bitter, that is a sign that you may have higher levels of copper, and you should get your water tested.
This is a matter of some debate, as there are pros and cons for each. PVC plumbing is much cheaper than copper plumbing, particularly since copper pipes have been increasing in cost steadily in recent years. PVC pipes are also easier to install, being lighter and more versatile. The issues arise once the system has been installed. While both PVC and copper will leach materials into the water, we do not have a full understanding of the materials leached by PVC or their effects. Copper has been in use for thousands of years, and as such there is more confidence that copper leaching is not harmful at normal levels. Plastics like PVC are relatively new, and the effects of their leached materials haven’t been as thoroughly studied yet.
Copper water pipes started becoming common in new North American homes starting in the 1930’s, and have remained more or less the go-to ever since. Lead pipes were in use prior to that but have mostly been replaced by now, for obvious reasons. Galvanized steel was also common until the 70’s. Plastic enjoyed a bit of a boom during the 1980’s and 90’s, but copper remains the leader in the present. Copper can be found in both old and new homes, especially homes built within the past 50 years or so.
The estimated cost to refit a 1,500 square foot home with copper plumbing could be anywhere from $10,000-$15,000. The cost of copper piping is about $2-6 per foot, depending on the size and type of pipe. Most of the cost of refitting a home comes from having to open up the walls and ceilings to access the plumbing. If you’re planning on refitting your home with a new plumbing system, it makes sense to do it during a larger renovation project when things are already being ripped open.
Galvanized steel was a popular choice for plumbing systems in the 20th century, but it’s fallen out of favour. Galvanized steel pipes are prone to rusting. If the pipes are really old, like pre-1960, they may have been treated with impure zinc, which can contain more lead than is advisable for a home plumbing system. Replacing galvanized steel with copper plumbing can increase the value of your home, and make it more attractive to home insurers. In fact, some insurers may ask you to replace your galvanized steel system before they will insure your home.
Some discolouration of copper is normal, as long as it’s green and inside the pipe. Green colouration on the outside may be a sign of leakage. Black colouration anywhere on the pipe is not normal. It’s often a sign that something is going wrong, and your plumbing is being corroded. The culprit may be water with a pH that is too high or too low. This is more common in well water systems, as city water should be treated to normalize the pH.
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