According to some estimates, copper pipe corrosion costs the United States more than $1 billion a year. Copper corrosion in home plumbing systems is a common phenomenon that can have many causes.

Besides actual piping failure, the telltale blue stains that the oxidized copper leaves on sinks, tubs, and fixtures can identify copper corrosion. These stains are the result of a chemical reaction between copper, water, and oxygen, leading to the formation of corrosion products such as copper carbonate, which gives the characteristic green patina.

Often, laundry and even blonde hair can be tinted blue. Copper pipe corrosion may cause toxic levels of copper and lead to contaminating your water. Water containing levels over 1.0 mg/L should not be used for drinking. Corrosion damage can progress from minor discoloration to extensive damage if left unaddressed, and even a small leak in the affected area can escalate quickly.

If there are iron pipes present, the water can be colored rust or reddish and contain metallic or sulfur odors and sediment. Pipe leaks often result from corrosion, and identifying the root cause of corrosion is essential to prevent further issues. Eventually, corrosion can cause the piping to fail, in some cases in less than 10 years. Various water quality factors can corrode copper pipes, and early detection and repair of small leaks can help avoid extensive damage.

What is Corrosion?

Blue stains in sinks are telltale signs of copper corrosion.

Corrosion is “the deterioration of a substance or its properties due to a reaction with its environment.”

In plain words, the metal from the piping dissolves into the water due to various causes, creating pipe failure and corrosion of water heaters, appliances, and fixtures.

Blue corrosion on copper pipes and plumbing systems is due to physical and chemical reactions between the pipe material and water. Copper alloys generally have excellent corrosion resistance because a protective film forms naturally on the metal’s surface, shielding it from further degradation. However, if this protective film is damaged or disrupted, it can lead to localized corrosion, where specific areas of the pipe corrode more rapidly.

The main causes of pipe corrosion are:

Low pH (acid water) is typically found on private well water but is also present in some small municipal water systems.
Other water chemistry causes high levels of dissolved oxygen, high levels of salts dissolved in the water, and/ or corrosion-causing bacteria such as sulfate or iron bacteria.
Electrochemical causes, such as the improper grounding of electrical appliances to the copper piping.
The high velocity of water, relative to the size of piping, causing hydraulic wear on the piping, for instance, a recirculating hot water system with a pump driving the water through pipes that are too small in diameter.
Poor plumbing installation practices, including not cleaning or de-burring the pipe properly and excessive flux in soldering the pipe fittings.
Sand, sediment, or other grit causing hydraulic wear on the piping.
Lightning strikes utility poles where the electricity travels to ground wires connecting to piping systems.
Environmental factors such as soil conditions and moisture can influence the rate and type of corrosion, especially in underground or soil-exposed copper piping.

Causes of Corrosion

Corrosion on copper pipes is a widespread problem that stems from a combination of water quality, environmental conditions, and installation practices. The oxidation process, where copper reacts with oxygen and moisture, leads to the formation of copper oxide and the characteristic green corrosion often seen on copper piping. Poor water quality, such as water with low pH, can accelerate this process, making pipes more susceptible to damage. High water velocity, especially in hot water pipes, can also wear down the copper surface, while poor aeration and temperature changes further contribute to the corrosion of copper pipes. Additionally, the presence of certain minerals or chemicals in the water, as well as exposure to moisture, can intensify the corrosion process, ultimately compromising the integrity of your plumbing system.

Signs of Copper Pipe Damage

Recognizing the early signs of copper pipe damage is crucial for maintaining a healthy plumbing system and preventing further corrosion. One of the most noticeable indicators is green discoloration or green patina on the copper pipe, which signals the presence of corrosion. Pinhole leaks are another common sign, often resulting in a slow leak that can cause water damage and lead to extensive corrosion if left untreated. These small leaks may seem minor at first but can quickly escalate into larger problems, including further damage to your pipes and surrounding areas. Regular inspections can help detect these issues early, allowing you to address underlying problems before they result in costly repairs or significant leaks.

Effects of Corrosion on Health

Corrosion in copper pipes can pose health risks, especially when it leads to elevated copper levels in your drinking water. While copper is an essential nutrient, excessive amounts can be harmful, particularly for infants, young children, and individuals with certain health conditions. The EPA has set an action level of 1.3 mg/L for copper in drinking water; levels above this threshold can cause gastrointestinal distress and, in severe cases, liver or kidney damage. Regular water testing and prompt attention to signs of corrosion are essential steps to ensure your water remains safe and to minimize health risks associated with corroded copper pipes.

What can be done? How to Clean Copper Pipe Corrosion

1. Identify the source and severity of the problem by inspection of the piping system and water analysis:

Check to see if there are unnecessary electrical appliances or wiring connected to the piping.
Do a first draw copper test. Find out how high the levels of your copper are. To do this wait overnight and draw some water and test for copper (this is called a “first draw test”) using a home copper test kit.
Check to see if the piping system is properly grounded. Verify that there is electrical continuity throughout the piping system.
Check for pH, hardness, alkalinity, total dissolved solids and see if the water is corrosive, and perform a Langelier Index.
You can use our Online Langelier Index Calculator.

2. Correct or minimize the cause of the corrosion above.

3. Install a calcite neutralizer tank or a soda ash feeder to raise the pH to 7.0 to 8.0 to correct for low pH and increase the water’s alkalinity.

4. Install a phosphate feeder before the copper piping. Phosphate will coat the piping and reduce or slow down the corrosion effects by coating the piping’s interior surfaces with phosphate and causing an insulation surface to be built up.

Calcite Neutralizer Filters

One of the most convenient methods to raise pH and add a little hardness and alkalinity is to use a calcite neutralizer filter. These filters will typically raise the water’s pH to 7.0 to 8.0 and add 30 to 100 ppm of hardness depending on the alkalinity and water hardness.

In neutralizer filters, acidic waters slowly dissolve the calcium and magnesium media on contact as the water flows through the filter, raising the water’s pH and increasing the alkalinity. This water system eliminates the effects of corrosive water chemistries and is a good solution for preventing copper pipe corrosion and corrosion of fixtures.

The size of the system is directly proportional to the flow rate of the water, in gallons per minute. The higher the flow rate, the larger the system required.

Neutralizer filter tanks are filled with a blend of calcium and magnesium carbonates made from naturally occurring minerals. These minerals dissolve into the water, making it less corrosive. More minerals can quickly and easily be added to the filter tank, typically once per year for most residential applications. No special tools are required.

This type of neutralizer also acts as a filter to remove sediment and small amounts of rust from the water and then backwash it out once every week.

Soda Ash Feeders

A small pump called a metering pump is used to inject a small amount of soda ash (sodium carbonate) into the water, usually combined with a contact tank.

For best results, allow a few minutes of contact with the water for pH adjustment and the soda ash solution to mix in the water using a contact tank thoroughly.

For home water wells the metering pumps are usually wired to turn on and start pumping soda ash solution when the well pump is energized or running.

Soda ash is bought dry, usually in 25 or 50 lb bags, and mixed with soft or pure water in the solution tank. When a saturated solution is achieved (approximately 3 pounds per 5 gallons of water, which creates a 10% solution), a solution of between 50 and 500 ppm is injected, depending on the pH, alkalinity, and flow rate of the water.

In some cases, instead of dissolved carbon dioxide causing the low pH or acidity, the acidity is caused by mineral acids, either natural or from mining or other industrial wastes. In this type of water, the pH is less than 5.0. A soda ash feed pump is used, or in some cases injection of sodium hydroxide is required.

Water Quality and Corrosion

The quality of your water plays a significant role in the corrosion process affecting copper pipes. Hard water, acidic water, and water containing high levels of minerals or chemicals can all contribute to the deterioration of copper piping. Substances like oxygen and chlorine in the water can accelerate corrosion, leading to further damage over time. To protect your plumbing, it’s important to conduct regular water testing and consider treatment options such as water softeners or neutralizers. Scheduling annual plumbing inspections with a licensed plumber can also help identify early signs of corrosion, address water quality issues, and prevent costly repairs down the line.

Preventing Future Corrosion

Preventing future corrosion in copper pipes involves a proactive approach that combines regular maintenance, proper installation, and environmental management. Using corrosion-resistant materials and applying a protective coating to the copper surface can help shield pipes from the elements. Regularly removing green corrosion from copper pipes with gentle cleaning methods, such as a paste of baking soda and water, can prevent further damage to the corroded area. Addressing underlying issues like poor water quality, temperature changes, and excess moisture is also essential to prevent future corrosion. Scheduling annual plumbing inspections and consulting a professional plumber can help you identify and resolve potential problems before they escalate, ensuring your plumbing system remains in top condition and helping you avoid costly repairs.

Test your water for pH
Corrosion Test Kits
Well Water Test Kits

Resources:

Read more about copper pipe corrosion on the Connecticut Dept of Health

Frequently Asked Questions (FAQs)

1. What is copper pipe corrosion?

Copper pipe corrosion is the gradual degradation of copper plumbing due to chemical reactions with water, air, or surrounding materials. It can lead to leaks, blue-green staining, and poor water quality.

2. What does copper pipe corrosion look like?

Corrosion appears as blue-green stains around faucets, drains, or on the pipe itself. You might also notice pinhole leaks, low water pressure, or cloudy water.

3. What causes copper pipe corrosion?

Common causes include acidic or low-pH water, high levels of dissolved oxygen, electrical grounding issues, and water velocity that’s too high for the pipe diameter.

4. How do you stop copper pipe corrosion?

Solutions include installing a calcite neutralizer for low pH, reducing water velocity, using dielectric unions, and upgrading to corrosion-resistant piping.

5. How to treat copper pipe corrosion?

Treat corrosion by testing your water, correcting pH levels, and replacing or repairing damaged piping. Installing a whole-house water treatment system can help prevent further issues.

6. How to clean copper pipe corrosion?

Small surface corrosion can be cleaned with a vinegar and salt solution or a commercial descaler. For internal corrosion or pinhole leaks, pipe replacement is often needed.

7. How to detect copper pipe corrosion?

Look for blue-green stains, low water pressure, leaks, or metallic-tasting water. Water testing can confirm pH imbalance or high corrosive potential.

8. How to repair copper pipe corrosion?

Repair methods include replacing sections with pinhole leaks, using push-to-connect fittings, or applying epoxy liners for larger corroded areas.

9. What are the signs of copper pipe corrosion?

Signs include discolored water, metallic taste, blue-green stains, visible corrosion on pipes, frequent leaks, and reduced water pressure.

10. Why is copper pipe corrosion a problem?

Corrosion leads to plumbing leaks, water damage, and contaminated water. Left untreated, it can cause expensive repairs and health risks from metal exposure.