Why are galvanized pipes often deemed unsuitable for water service?

Galvanized pipes are often considered unsuitable for water service primarily due to their susceptibility to galvanic corrosion. This specific type of corrosion occurs when galvanized pipes, made from zinc-coated steel, come into contact with dissimilar metals in the plumbing system, such as copper or brass. The electrochemical reaction can lead to the deterioration of the zinc coating, exposing the underlying steel to moisture, which results in rust and corrosion. Over time, this weakens the pipes and can lead to leaks or pipes bursting.

While other factors such as lifespan and repair costs may be considerations in a broader context of plumbing materials, the particular concern for galvanized pipes lies prominently in their propensity for galvanic corrosion when mixed with other metals. As a result, many water systems are moving towards alternatives such as PVC or PEX for their improved longevity and resistance to corrosion.