Across the country, utilities are moving fast to meet lead service line replacement (LSLR) mandates. One question we often hear is whether copper tubes are safe choices in applications where they’re embedded in or come into contact with concrete. This concern usually comes from outdated assumptions about corrosion.
Here’s the truth: copper performs reliably in concrete when installed properly. It has done so for over a century in water distribution systems, radiant heating, and snow melt applications. Crews can feel confident specifying copper for projects where concrete is part of the build.
Let’s take a closer look at how copper holds up in concrete and why utilities continue to rely on it in these environments.
Contractors and municipalities have used copper in concrete-embedded systems for decades. These installations have stood the test of time without signs of pitting, corrosion, or failure. Radiant heat systems and snow melt lines placed in slab or wall pours continue to perform with no degradation.
The Copper Development Association (CDA), Portland Cement Association, and international researchers all agree that both hard-drawn and annealed copper tube can be safely embedded in concrete. Proper installation ensures that they perform without compromising water quality or structural performance.
Independent research by the Centre Expérimental de Recherches et d’Études du Bâtiment (C.E.R.B.P.) confirms what the field shows. Researchers placed copper and iron samples into concrete and plaster under changing conditions, including wet-dry cycling, capillary action, and heat exposure.
The copper showed no corrosion in any condition. Iron, on the other hand, began rusting early in the test. It deteriorated further when electrically coupled with other metals or exposed to chloride admixtures.
Voltage readings between copper and surrounding materials stayed within safe levels. During wet concrete testing, the maximum variation in corrosion potential was -90 mV. After 40 days of cycling, copper remained stable.
These findings match what contractors have seen in the field for decades. When installed properly in well-mixed, cured cement, copper holds its integrity over time.
Clearing Up Common Concerns
Here are three issues we often hear about that do not stand up to current research and installation experience.
Lime in Concrete
Lime does not attack copper. Hydrated cement creates an alkaline environment that is non-corrosive to copper. In fact, pulverized limestone is often used as backfill around buried copper pipe because of its chemical stability.
Moisture in Concrete
Fresh concrete and the soil under many buried installations contain moisture, but moisture alone does not trigger corrosion in copper. CDA research and testing from C.E.R.B.P. show that copper embedded in both wet and dry concrete does not degrade. The risk only increases when copper is improperly installed or exposed to corrosive agents such as chlorides or direct electrical contact with dissimilar metals.
Movement from Thermal Expansion
Copper expands and contracts slightly with temperature changes. This behavior is predictable and manageable. In embedded systems, contractors should use sleeves, foam insulation, or plastic wraps where copper enters or exits concrete structures. These measures allow for controlled movement and protect against abrasion or stress at penetration points. Most plumbing codes already require this kind of protection.
AWWA’s article Conditions Contributing to Underground Copper Corrosion reinforces the case for copper. While the article focuses on buried pipe systems, its conclusions also apply to embedded systems.
Copper typically corrodes at a very low rate in soil and concrete. Risk increases when copper comes into direct contact with other metals, such as steel or iron, in the presence of moisture. When chloride-based admixtures like calcium chloride are added to the mix, the likelihood of galvanic corrosion rises.
These conditions are preventable. Wrapping the copper in plastic, using dielectric sleeves, or maintaining physical separation are all effective mitigation techniques. In highly aggressive environments or low-resistivity soils, contractors can use clean sand or limestone backfill to further reduce corrosion risk.
These AWWA recommendations match CDA’s technical guidance. Together, they provide a consistent roadmap for safe copper installation in concrete infrastructure.
Utilities and contractors can extend the service life of embedded copper by following five core practices.
Ensure Full Embedment
Copper tube should be completely surrounded by concrete. Partial embedment can expose the pipe to air gaps, moisture intrusion, or mechanical stress points. Full embedment supports structural integrity and long-term corrosion resistance.
Provide room for expansion and contraction where copper tube enters or exits concrete. Use watertight sleeves, insulation, or approved plastic wraps to reduce abrasion and accommodate pipe movement over time.
Copper should not come into direct contact with ferrous metals, such as steel or cast iron, within the same concrete pour. If these metals are present, use non-conductive spacers, dielectric unions, or coatings to separate them and prevent galvanic activity.
Do not use calcium chloride or other chloride-rich admixtures in concrete that will touch copper tube. If such admixtures are present due to legacy materials, apply isolation techniques to shield the copper from exposure.
High-density, low-permeability concrete offers the best performance for embedded systems. Properly cured concrete limits moisture migration and preserves pH balance, which supports long-term copper stability.
Copper has been used in embedded systems for decades without widespread failure. Its track record covers everything from residential foundations to large institutional facilities. Crews continue to choose copper because they know it performs. It installs cleanly, resists corrosion, and lasts for generations.
As utilities expand their LSLR programs and modernize water infrastructure, copper remains a trusted solution. It is familiar to contractors, acceptable under most codes, and backed by both lab and field performance.
Copper tube performs in concrete. The science backs it. The field proves it. And the installation guidance is clear. When embedded using proper techniques, copper is a durable and reliable material for service line replacement, vault installations, and foundation-embedded systems.
For more information on this topic, please review the following articles:
Request a free Do It Proper with Copper training from CDA and get hands-on support for your LSLR program.