Journal of Failure Analysis and Prevention

, Volume 4, Issue 4, pp 38–42 | Cite as

Microbiologically influenced corrosion in hydronic heating systems

  • R. A. Clark
  • D. R. Clark
Peer Reviewed Articles


Open-loop hydronic heating systems have been found to provide a breeding ground for bacteria, including bacteria associated with microbiologically influenced corrosion (MIC). Microbiologically influenced corrosion of brass fittings, which may contain up to 8% lead in potable water applications, has been linked to high copper and lead levels in water samples taken from the hydronic-loop tubing. The contamination is likely concentrated in slime deposits found within the tubing. These slime deposits can enter the potable water supply, resulting in potential copper and lead exposure levels considerably above Environmental Protection Agency (EPA) guidelines. The authors recommend that hydronic heating systems incorporate a closed-loop design to prevent personal exposure and to provide for use of corrosion-inhibiting additives.


brass fittings corrosion hydronic heating MIC potable water 


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  1. 1.
    J. Siegenthaler: Modern Hydronic Heating for Residential and Light Commercial Buildings, Delmar Publishers, Albany, NY, 1995, pp. 1–10.Google Scholar
  2. 2.
    Atlas of Microstructures of Industrial Alloys, vol. 7, Metals Handbook, 8th ed., American Society for Metals, Metals Park, OH, 1972, p. 290.Google Scholar
  3. 3.
    E.D. Verink: Corrosion Basics and Introduction, L.S. Van Delinder, ed., National Association of Corrosion Engineers, Houston, TX, 1984, p. 352.Google Scholar
  4. 4.
    “Legionella 2003: An Update and Statement by the Association of Water Technologies (AWT),” June 2003, pp. 8–9.Google Scholar
  5. 5.
    G. Schick: “Corrosion in the Presence of Sulfate-Reducing Bacteria,” Water and Waste Water Microbiological-Influenced Corrosion in Water Systems; Corrosion Information Compilation Series, NACE International, Houston, TX, 1999, pp. 136–45.Google Scholar
  6. 6.
    “Ground Water and Drinking Water: Actions You Can Take to Reduce Lead in Drinking Water,” EPA 810-F-93-001, United States Environmental Protection Agency, June 1993.Google Scholar
  7. 7.
    R. Parrington: “Biological Corrosion Failures,” Failure Analysis and Prevention, vol. 11, ASM Handbook, W.T. Becker and R.J. Shipley, ed., ASM International, Materials Park, OH, 2002, p. 890.Google Scholar

Copyright information

© ASM International 2004

Authors and Affiliations

  • R. A. Clark
    • 1
  • D. R. Clark
    • 1
  1. 1.GT EngineeringRedmond

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