Why do copper pipes turn green?
Copper turns green due to oxidation, which is the removal of electrons from the substance. The copper, in particular, turns green due to a substance known as copper carbonate. The big question, however, is why does copper carbonate appear?
When a metal is exposed to air or water, it undergoes environmental changes. In other words, it could rust or tarnish. Copper tarnishes and turns green over time.
The previous plumber who worked on the property did not clean the pipes properly.
This can cause your pipes to leak or burst.