MIB and Geosmin Testing Specialist - Regional Water Authority LabMIB and Geosmin

The main cause of taste and odor in drinking water can be attributed to the microbial production of (−)-geosmin [(−)-(4S,4aS,8aR)-4,8a-dimethyloctahydronaphthalen-4a-ol] and MIB ( (−)-2-methylisoborneol) {(1R-exo)-1,2,7,7-tetramethylbicyclo[2.2.1]heptan-2-ol}. The concentration of these compounds in parts per trillion will cause an earthy musty odor.

Geosmin and MIB are tertiary alcohols produced by members of certain groups of benthic and pelagic aquatic microorganisms. Geosmim and MIB are found in source waters such as lakes, reservoirs and running water like streams and rivers. Cyanobacteria, also called blue-green algae, are some of the major producers of these compounds.

Cyanobacteria are a photosynthetic nitrogen-fixing bacteria that survive in a wide variety of habitats, soils and water. The photosynthetic pigments in cyanobateria are cyanophycin, allophycocyanine and erythrophycocyanine. Their thalli vary from unicellular to filamentous and filamentous heterocystous. They fix atmospheric nitrogen in aerobic conditions by heterocyst, specialized cells, and in anaerobic conditions.

It has been documented that post-treatment production of geosmin due to biological activities can result in odor issues downstream of water treatment and throughout the distribution system. Geosmin and 2-MIB are stable compounds and persist in open water in a dissolved form for extended periods of time. The stability of these compounds makes it difficult for conventional filtration to oxidize and eliminate the problem. Early detection can allow treatment and intake modification to eliminate or reduce the intensity of the problem.