Metallic materials in Danish supply water systems

Characteristic corrosion phenomena and materials selection in hard supply water areas in Denmark are reviewed. Both corrosion failures and metal release are described. Even though good protective layers can be formed in the majority of cast iron pipes, the ease of installation and the corrosion resistance of plastic pipes result in the use of medium- and high-density polyethylene and polyvinylchloride (PEM, PEH and PVC) for new pipes. Corrosion is problematic in domestic pipes. Due to localised corrosion, selective attack of the zinc-layer and zinc release, galvanised steel gives too many problems. The copper release from copper pipes is too high after stagnation. The tendency is to preferentially use the more resistant materials such as stainless steel and crosslinked polyethylene (PEX), for domestic pipes. Possible higher microbial growths in plastic pipes are under investigation.