What could be causing multiple pinhole leaks in copper supply lines, and would switching to PEX be a better solution during a major remodel?
Asked by Ümit Beşerler 
2 months ago
Last Updated: July 30, 2024
What could be causing our copper supply lines to keep springing pinhole leaks? We’ve had about twelve leaks in the past half-year.
Our house was built in 1991, so I’m wondering if it’s just low-quality copper piping that’s finally giving out.
We’re actually starting a big remodel to expand our master bath and closet, and it seems like a good idea to replace those supply lines with PEX. The plumbing is getting redone in that whole end of the house anyway, so it makes sense to upgrade.
We got a tankless water heater about five years ago and never had any leaks until recently – so something must be going on with the pipes.
If you’ve had problems after 30 years, it’s probably not the pipe itself. It might be due to electrolysis or poor water quality. It’s best to repipe your home instead of constantly repairing it.
Flaherty, just wanted to update you that we’re getting PEX installed to replace all the lines this week while our master bath is being renovated.
Great! Make sure to remove all of the piping while you’re working on it.
Do you happen to have a water softener?
Hey there, I was actually talking about our tankless water heater and how our town has the best water quality ratings. I’m curious to know more about why this might be happening and if it could be affecting anything else.
Hey Dora! Just wondering if there have been any recent changes in the plumbing at your house or in the neighborhood. Your water quality is usually top-notch, but have you considered getting it tested at a pool store or using a water test kit to check for any minerals that could be affecting it?
Hasn’t checked the water yet, but thinks it’s a good idea. I don’t know of anything in the neighborhood… there are only 13 homes in our Subdivision and we all keep in touch. Two other homes (built by the same builder) are experiencing problems, including issues with their copper pipes.
It might not be that the copper was low quality, but rather the mineral content in the water. When water moves too quickly through the pipes, it can cause damage to the lining. Slowing down the water flow or getting a whole house water softener could be helpful. Normally, copper should last 20-50 years, but if there’s a lot of leakage, it’s probably best to consider replacing it.
Are the pinholes close to the joints? Maybe within 6 inches?
It’s more than 6 inches but less than a foot. There are 4 spots on this 3 feet of pipe that seem like they’re about to fail (do you notice the patina forming?)
Could you take a closer look at those two elbows?
Hey, , the elbows were put in by the plumber who installed the tankless water heater.
Hey, , if he forgot to smooth out the inside of the copper when he cut it, it could lead to turbulence and eventually a pinhole leak. The only sure way to know is to remove it and inspect.
Hey, , have you remembered to keep up with your descaling schedule?
Hey , do you know what the descaling schedule is for? Is it recommended as part of the annual service/inspection for tankless systems?
All of it will be swapped out within the next 10 days.
Yes, , descaling is a necessary maintenance task for tankless water heaters.
Is water dripping onto it from above? I noticed what appears to be water damage.
I had the same thought… that is actually the wood grain. I checked for myself. The plumber is scheduled to come tomorrow to switch everything out with PEX.
It’s really weird how copper pipe doesn’t last as long as you’d expect. It might be worth checking the thickness of the walls around any pinholes. You could also test the pH of the water to see if it’s acidic.
I would also inspect those fittings and check if they were ever reamed out because turbulence can damage pipes over time.
Every single part of my 1954 house is made of copper. This includes the drainage, ventilation, and water systems. We only experienced one leak in the basement laundry room 2 years ago. We had a tankless water heater installed 11 years back. The new plumbing in the photo was added by us when we put in a master bathroom on the upper floor.
New copper pipe is actually thinner than older copper pipe. Over time, the pipes can wear down due to friction from the water. Certain chemicals in the water, such as chlorine or fluoride, can speed up this process.
I think the wall thickness for Type M, L, and K has been the same for a while.
This problem is quite common during that particular time period due to poor quality copper pipes being used. In some cases, the incorrect thickness of pipes intended for potable water may have been utilized. It’s worth noting that heating systems typically use thinner, cheaper copper pipes with a lower PSI rating.
If you test your water, you will likely discover that it has an acidic pH level that can corrode copper pipes. This is a common issue with well water and sometimes even town water. It is advisable to replace these copper pipes with pex pipes that have plastic elbows and fittings. Additionally, this corrosion can sometimes affect the taste of the water. Alternatively, using cheap Chinese pipes that are too thin can also lead to problems, although there are pipes available in various thicknesses, it’s important to make sure they meet code requirements.
Caused by the water treatment process carried out by your local utility water company. Essentially, alum is added to help settle suspended particles, but it ends up reacting with the copper and causing erosion from the inside. This issue is well known in the GM water in East Texas. All of my neighbors have had to replace their pipes with pex due to this, and now mine is leaking as well. It was built around the same time frame you mentioned.
Water with a low pH, also known as acidic water
Update: The plumbers showed up at 8am this morning to deal with another new leak. After opening up the ceiling sheetrock and finding two more spots leaking, they decided to tackle the entire project in one day. The work took over 12 hours, but they have now finished replacing all the supply lines. This is a huge relief because I won’t have to worry about any more costly emergency plumbing visits or unexpected leaks. They also installed two new hose bibs and a whole house shut-off valve for convenience. The sheetrock repair will be done in the next few days.
Let’s reschedule for next week.
Please email me the details instead.
I cannot attend the meeting tomorrow.
The movie starts at 7 PM sharp.
Remember to pick up some groceries on your way home.
I am excited to see you tonight!
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