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What Causes Pinholes in Copper Pipes

Boiler room with insulated pipes and fire stops.

Copper pipes have been a popular choice for homeowners for years because of their durability, longevity, and resistance to corrosion (although they sometimes do encounter green corrosion). However, there is one issue they encounter that should be addressed as soon as possible: pinholes in copper pipes. These tiny but problematic holes can lead to leaks, property damage, inconveniences in your home, and costly repairs. Here, we will delve into what causes pinholes in copper pipes, their impact, and our expert solutions. 

Understanding Copper Pipes

Before we answer the question of what causes pinholes in copper pipes, it’s helpful to understand copper pipes themselves. They typically come in two varieties: rigid copper pipes and flexible copper pipes, often called copper tubing. Keep reading to learn more about the differences! 

Rigid Copper Pipes

Rigid copper pipes are solid and can withstand high pressures. They are commonly used for water supply lines in commercial and residential systems. They are available in various sizes, but Type L and Type M are the most common. 

Copper Tubing

This type of copper pipe is more flexible and often used for water distribution, such as connecting fixtures and appliances. Copper tubing can be found in both hard and soft varieties, soft being more prevalent in residential plumbing systems because of its flexibility and ease of installation. 

What Causes Pinholes in Copper Pipes

Now that you know about the different types, we can investigate what causes copper pipe pinholes. 

Water Quality

Water quality is one of the primary factors that contribute to what causes pinholes in copper pipes. Water that is acidic or has a low pH can corrode the interior surface of the pipes over time. The corrosion gradually weakens the pip walls, which leads to pinholes and further complications down the line. 

Chemical Reactions

Copper is reactive to certain chemicals commonly found in water. Exposure to chloramines can cause a reaction with the copper, causing corrosion and the development of pinholes. 

High Water Velocity

Excessively high water velocity, often caused by oversized pumps or high-pressure systems, can result in the erosion of the interior surface of copper pies, leading to small pits, which can eventually turn into pinholes. 


Waterborne particles and sediment move within the pipe and can wear down the inner surface. Over time, the pipes can wear down enough that tiny openings form, turning into pinholes. 

Microbiologically Influenced Corrosion (MIC)

MIC is a process that involves the interaction between microorganisms and the copper pipe’s surface. These microorganisms produce corrosive byproducts that can accelerate the pinholes by wearing down the pipes. 

Improper Installation

Pinholes are not always due to typical wear and tear but can cause improper installation. These include excessive soldering heat or poor soldering, which weakens the pipe from the beginning. 

Fluctuations in Water Temperature

Frequent temperature fluctuations in the water flowing through copper pipes can contribute to stress on the pipe. Over time, the pipe’s integrity can weaken, making it more susceptible to the formation of pinholes. 

The Impact of Pinholes in Copper Pipes

While determining what causes pinholes in copper pipes is important, it’s also important to understand the impact. While the pinholes are small, their impact can be significant and wide-ranging. 

Water Leaks

The most immediate consequence of pinholes in copper pipes is water leaks. The leaks can lead to property damage and potential mold growth. 

Water Pressure Loss

Pinholes can also reduce pressure in affected pipes, impacting the overall performance of your water pressure throughout your home. 

Water Quality Issues

Water that flows through copper pipes with pinholes can pick up contaminants that will affect the quality of water that you use for consumption, bathing, cleaning, etc. 

Energy Loss

Leaking pipes can result in energy loss, as hot water escapes from the system before reaching its destination, which will increase your bills. 

Repair Costs

Knowing what causes pinholes in copper pipes can help you avoid costly repairs. If issues are widespread or located in hard-to-reach areas, you might have an expensive project to deal with. To avoid this, it’s best to schedule regular maintenance to fix any issues as soon as possible. 

Solutions and Preventive Measures

While pinholes in copper pipes can be a nuisance, there are several solutions and preventative measures that homeowners and plumbing professionals can implement. 

Water Quality Testing

Regularly test your water quality to determine its pH level and chemical composition. If your water is too acidic or contains corrosive elements, consider water treatments. If you are unsure which is the best for you, contact the team at Goodbee Plumbing and we are happy to lend our expertise! 

Proper Installation

Ensure that copper pipes are installed correctly. The best way to ensure this is to work with a plumbing partner that you can trust! At Goodbee Plumbing, we want to clean your drains, not your wallet, so contact us today to schedule your service

Pressure Regulation

Install pressure-reducing valves (PRVs) or flow restrictors to control high water pressure, which reduces the risk of erosion and corrosion. 

Regular Maintenance

Implement a routine maintenance schedule to locate any issues before they become big problems! Things to inspect include flushing the lines, inspecting for sides or corrosion or pitting, and double-checking everything is running properly. 

Water Filtration

Consider installing water filtration systems to remove particles and sediment from your water to reduce the abrasion inside the pipes.

Never Again Ask, “What Causes Pinholes in Copper Pipes” and More by Partnering with Goodbee Plumbing

Now that you know what causes pinholes in copper pipes, you can work to ensure your plumbing system works efficiently. Understanding the causes, impacts, and solutions is essential to maintain a reliable and safe plumbing system. While pinholes can occur, preventive measures and the expertise of those at Goodbee Plumbing can address and mitigate these issues to ensure your plumbing system has the longevity it deserves. 

If you suspect pinholes or require our expertise for any other plumbing issue, contact us today! 

And if you are a DIY person, check out our blog for projects you can do on your own! But remember, if you ever are unsure, it’s best to rely on the professionals!

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