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Excessive pitting corrosion can lead to pinhole leaks in the pipe and result in water damage and mold growth.Ĭonditions That Can Promote Copper CorrosionĬertain conditions can cause corrosion when copper is exposed to particular soils, including: Non-uniform corrosion, which is the isolated development of corrosion cells across the inner surface of a pipe wall.It is typically associated with elevated copper levels at the taps. Uniform corrosion, which is identified by the presence of a relatively uniform layer of copper corrosion byproducts across the inner surface of a pipe wall.Fortunately, the protective film on copper usually remains intact and repairs itself in most soils. If this protective film, usually consisting of reddish-brown cuprous oxide (Cu 2O), is destroyed, then copper will eventually corrode. The metal is basically immune to corrosion due to a naturally occurring protective film known as a patina that forms on the metal's surface.

If testing of pipes reveals a level greater than 1.0 milligram per liter (mg/l), then treatment is necessary.Ĭopper is considered to be a noble metal, and as a result is able to resist attack by oxygen. High copper levels over time can lead to liver or kidney damage. A small amount of copper consumption is acceptable for humans because it serves as an essential nutrient, but too much may cause gastrointestinal problems. However, it is susceptible to more rapid attack in oxidizing acids, oxidizing heavy-metal salts, sulfur, ammonia, and some sulfur and ammonia compounds.Ĭopper can be toxic and can leach into tap water in both old and new homes. Copper is also susceptible to crevice corrosion attack.Ĭopper corrosion occurs at negligible rates in unpolluted air, water and deaerated non-oxidizing acids. There are two known types of copper corrosion, which are uniform copper corrosion and non-uniform copper corrosion. After a few years, this tarnish gradually changes to dark brown or black, and finally to green. When exposed to the atmosphere, copper oxidizes, causing normally bright copper surfaces to tarnish. Copper corrosion is the corrosion of materials made of copper or copper alloys.