Pinhole Leaks in Copper Pipes Explained

2017 May 19
Posted in: Plumbing

Uh-oh. You’ve heard about those tiny, destructive openings in copper pipes called pinhole leaks, and now you’d like to know what they’re all about.

It’s good that you’re curious, because pinhole leaks can cause your home’s entire plumbing system to fail—not to mention cost you a small fortune on your utility bills.

You’ve come to right place to learn more. In this article, we’ll answer these 3 questions:

  1. What causes pinhole leaks in copper pipes?
  2. How do I know I have pinhole leaks?
  3. What are my options if I have pinhole leaks?

Let’s look at each of these questions in more detail:

#1: What causes pinhole leaks in copper pipes?


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Pinhole leaks occur when corrosion inside copper pipes finally breaks through to the outside of the pipe. 

Many homeowners ask us, “I thought copper was one of the most durable materials for pipes, how is it they can leak?”

It’s true: copper pipes are frequently used and preferred by plumbers because they’re generally resistant to corrosion and plumbers can easily shape them.

If that’s the case, how can copper pipes leak?

The #1 reason why copper pipes leak is due to turbulence. Turbulence enters your system in 2 ways:

  1. Velocity: Plumbing code limits the velocity within your piping system to 8 fps (feet per second) for cold water and 5 fps for hot water. Limiting the velocity reduces the turbulence in the pipes that creates pinholes. 
  2. Fittings that are too close together: Fittings that are too close together increase turbulence, which causes pinhole leaks. When fittings are too close together, turbulence in the water flow increases, which means the water grates against the inside wall of the pipe causing it to leak. Plumbing code specifies how close fittings can be placed next to another fitting. The distance between fittings is usually with 5 pipe diameters. For example, if you have a 90° fitting on a ½” tube, you must have a minimum of 2½” of space before you can apply your next fitting.

Another reason why your copper pipes have leaks is what’s called pitted corrosion, an extremely localized type of corrosion that attacks small areas on the inside surface of copper pipes.

Well, there hasn’t been a conclusive study on what causes pitted corrosion, here are some possible theories:

  • High levels of chlorine in the water supply
  • Corrosion particles from rusted water heaters
  • High water pressure
  • High pH levels in the water
  • Other chemical factors in soil and water (microbial activity)

Pitted corrosion is hard to detect without the help of a professional, but if it’s caused pinhole leaks, you’ll be able to tell with these signs...

#2: How do I know I have pinhole leaks?

If you notice any of the following signs, you may have pinhole leaks…

  • Your pipes look dimpled
  • The copper is starting to look weathered
  • Your water bills are more expensive
  • You hear dripping
  • You see water stains or discoloration on your walls
  • Your home has developed mold or mildew

Those are signs that point to already severe pinhole leaks. A plumber can inspect your piping to confirm you have pinhole leaks. However, because early signs of pinhole leaks are difficult to detect by the naked eye, the best way to check your copper pipes is by having annual plumbing maintenance by a certified plumber.

#3: What are my options if I have pinhole leaks?

Let’s say your plumber tells you that your copper pipes have pinhole leaks. What are your options?

Your options basically boil down to repairing the individual leaks or repiping your whole home. We’ll go into what option you should choose:

Option #1: Repair individual pinhole leaks

You should normally repair a single pinhole leak (instead of completely repiping your home) when…

  • This is your first pinhole leak, or you get very few leaks per year.
  • Your copper plumbing is less than 20 years old. Copper pipes can last 20–50+ years. So if your copper piping is less than 20 years old, it’s likely not fully corroded.
  • Your leak is located on a solder joint, elbows or tees. These areas corrode most quickly, so you can most likely repair that isolated spot and expect that other areas of your piping are still healthy.
  • The pinhole leaks are all located in the same piece of pipe. If your pinhole leaks are all on the same piece of pipe, you can most likely replace that stretch of pipe instead of repiping your entire home.

If you do have to repair individual pinhole leaks, we recommend adding a water filtration or softening system to prevent future pinhole leaks. Water filtration and softening reduce hard water deposits, which can cause leaks over time because they act like sandpaper against your pipe’s walls. A plumber can test your water for chlorine levels and total dissolved solids to see if a filtration system could prevent future leaks. 

Option #2: Repipe your home

You’ll have to repipe your home when…

  • You have 3 or more pinhole leaks within 6 months or less. When pinholes appear with greater frequency, it means there’s extensive pitted corrosion throughout your plumbing pipes. You’ll want to hire a professional to repipe your home if that’s the case because otherwise your risk severe water damage down the road.
  • Your copper plumbing is 20+ years old. The older pipes get, the weaker they become. So if your copper plumbing is 20+ years old, and you’re getting frequent leaks, you should consider repiping your home.
  • There are frequent leaks occurring in straight pipe runs. Straight pipe runs generally get the least amount of corrosion. So if you start getting pinhole leaks in multiple straight pipe sections of your copper piping, this indicates your piping is about to give out and that it should be replaced.

If you have to repipe your home for any (or all) of the above reasons, we recommend replacing copper pipes with PEX piping. PEX pipes resist corrosion, plus they’re cheaper and easier to install than copper pipes.

Think you have pinhole leaks? Need a reliable plumber?

Contact George Brazil Plumbing to schedule an appointment with one of our certified plumbers. We’ll check your pipes for any pinhole leaks, and we’ll figure out the best option to fix your home’s plumbing system if there are any issues.

We’ve been serving Arizona families since 1955.

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