What Is Galvanic Corrosion in Plumbing?

This process relies on three key components: an anode, a cathode, and an electrolyte. Two dissimilar metals, such as a steel pipe connected to a brass fitting, create the anode and cathode. The water in your plumbing system serves as the electrolyte, allowing a tiny electrical current to flow between them. This current forces one metal to corrode in order to protect the other.

The first clue is often a small, persistent leak, especially at joints between different-colored pipes. You might see discolored water, a blue-green stain from copper or a reddish-brown stain from steel rust. Low water pressure can indicate buildup inside the pipe from corrosion. In advanced cases, you may find a pinhole leak that sprays water, causing sudden damage to your home.

• Recurring leaks at pipe joints or fittings.
• Discolored water, often blue-green or rusty.
• Visible corrosion or crusty deposits on pipe surfaces.
• A metallic taste or smell in your tap water.
• Unexplained drops in home water pressure.
• Small pinhole leaks that spray water onto walls or cabinets.

A plumber can install dielectric unions or brass fittings to separate dissimilar metals, breaking the electrical circuit. They might also recommend replacing entire sections with compatible materials like PEX plastic piping. Regularly inspect visible pipes for early signs of corrosion or moisture. Check areas under sinks and near the water heater, as these are common spots for connections between different metals.